Nano imbibition oil-displacing agent as well as preparation method and application thereof

Abstract

The invention discloses a nano imbibition oil displacement agent as well as a preparation method and application thereof. The preparation method of the nano imbibition oil-displacing agent comprises the following steps: reacting citric acid, glucose, long-chain amine, a surfactant, an organic solvent, short-chain alcohol and water at 140-200 DEG C under 0.4-0.5 MPa for 6-16 hours to obtain the nano imbibition oil-displacing agent. The method disclosed by the invention is simple, convenient, environment-friendly and low in cost, and the prepared nano imbibition oil displacement agent has good surface and interface activity at high temperature and high salt, can be used as an imbibition oil recovery agent for an ultra-low permeability reservoir, and can remarkably improve the oil recovery rate.

Description

Technical Field

[0001] The invention belongs to the technical field of oilfield chemistry, and in particular relates to a nano-imbibition oil-displacing agent and a preparation method and application thereof. Background Art

[0002] With the deepening of oil exploration and development, the proportion of low-permeability oil resources is increasing, especially in recent years, the reserves of newly discovered ultra-low permeability oil reservoirs in my country are particularly rich. Therefore, the efficient development of ultra-low permeability oil reservoirs is an important direction for the development of my country's oil industry. Ultra-low permeability oil reservoirs are nanopores with high capillary force. Giving full play to the imbibition and displacement effect is one of the effective ways to develop them efficiently. The imbibition effect 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, mineralization, etc.), temperature, pressure, etc. Among them, wettability is one of the important factors affecting imbibition. Generally speaking, the more hydrophilic the rock pore wall is, the better the imbibition effect. At the same time, the reduction of crude oil viscosity can also effectively improve the imbibition effect. In addition, under different permeabilities, there is an optimal oil-water interfacial tension range for imbibition. Surfactants can change the wettability of rocks and reduce oil-water interfacial tension and crude oil viscosity. Therefore, surfactants can improve oil recovery by enhancing imbibition, which has been confirmed in field tests, but surfactants have limited effects on rock wettability.

[0003] Wasan et al. studied the spreading behavior of nanoparticle suspensions (nanofluids) on solid surfaces and proposed for the first time that nanoparticles form a solid-like ordered structure in a confined three-phase (solid-oil-water) contact zone. This structuring phenomenon of nanoparticles generates separation pressure in the wedge-shaped film, which promotes the spreading of nanofluids on the solid surface. Therefore, nanofluids can be used for soil remediation, oil 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 regulating the concentration of nanofluids, the size of nanoparticles and the size of interfacial tension, the spontaneous spreading of nanofluids on solid surfaces driven by structural separation pressure can be achieved when the contact angle is not zero. When the contact angle is large, small-sized nanoparticles are more likely to form a layered structure, thereby enhancing the spontaneous spreading of nanofluids on solid surfaces driven by structural separation pressure. It can be seen that the spontaneous spreading of nanofluids on solid surfaces with relatively low hydrophilicity can be achieved by reducing the size of nanoparticles. Therefore, enhancing the wettability of rocks by nanofluids, thereby effectively improving the efficiency of imbibition oil recovery in ultra-low permeability reservoirs, is a current research hotspot. Long Xueli et al. constructed a nanofluid imbibition agent using amphiphilic grafted modified nano-silica particles, betaine-type surfactants and non-ionic surfactants (CN 113717709B). Luo Mingliang et al. prepared a nano-magnetic fluid fracturing fluid imbibition oil enhancement system suitable for tight reservoirs using oleic acid-modified magnetic ferroferric oxide nanoparticles (CN110454132B). Wu Wenwei et al. polymerized raw materials containing double-bond modified lamellar nanomaterials, hydrophilic monomers and hydrophobic monomers to obtain a temperature-resistant and salt-resistant nano-imbibition oil displacement agent and its preparation method and application (CN 114410286A). Jiang Lihua et al. prepared a temperature-resistant and salt-resistant nano-imbibition displacement agent for low permeability reservoir oil displacement using nano-surfactants, non-ionic surfactants, amphoteric surfactants and low-carbon alcohols, in which the size of the nano-surfactant was less than 200 nm (CN114774096B).

[0004] Although the above nano-scale oil displacement materials have achieved certain effects in improving oil recovery, the above nano-scale materials are large in size for the nano-scale pore throats of low permeability reservoirs, have no amphiphilicity and have poor interfacial activity. Therefore, the present invention proposes a nano-scale imbibition oil displacement material based on ultra-small size and high interfacial activity. Summary of the invention

[0005] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a nano-imbibition oil-displacing agent and a preparation method and application thereof, so as to solve the problem that the existing nano-oil-displacing materials cannot meet the development requirements of low-permeability oil reservoirs.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions: On the one hand, the present invention provides a method for preparing a nano-imbibition oil-displacing agent, comprising the following steps: reacting citric acid, glucose, a long-chain amine, a surfactant, an organic solvent, a short-chain alcohol and water at 140-200° C. and 0.4-0.5 MPa for 6-16 hours to obtain the nano-imbibition oil-displacing agent.

[0007] Preferably, in percentage by mass, the amount of citric acid is 0.5% to 2%, the amount of glucose is 0.5% to 4%, the amount of long-chain amine is 0.25% to 2%, the amount of surfactant is 5% to 8%, the amount of organic solvent is 3% to 6%, the amount of short-chain alcohol is 10 to 15%, and the balance is water.

[0008] Preferably, the long-chain amine is a C8-C16 alkylamine, for example, octylamine, decylamine, dodecylamine, tetradecylamine or hexadecylamine.

[0009] Preferably, the surfactant is a betaine surfactant.

[0010] Preferably, the betaine surfactant includes one or more of lauramidopropyl betaine, cocamidopropyl betaine, oleamidopropyl betaine, lauramidopropyl hydroxysulfobetaine, cocamidopropyl hydroxysulfobetaine, and oleamidopropyl hydroxysulfobetaine.

[0011] Preferably, the organic solvent is one or more of xylene, toluene and limonene.

[0012] Preferably, the short-chain alcohol is a C2 to C6 alcohol.

[0013] Preferably, the short-chain alcohol is one or more of ethanol, isopropanol, n-propanol, ethylene glycol, and propylene glycol.

[0014] In a second aspect, the present invention provides a nano-imbibition oil-displacing agent, which is prepared by the preparation method described in the first aspect.

[0015] In a third aspect, the present invention further provides a use of a nano-imbibition oil-displacing agent prepared by the preparation method described in the first aspect in oil displacement in low permeability reservoirs.

[0016] The beneficial effects of the present invention are: The present invention uses citric acid, glucose, long-chain amine, surfactant, organic solvent and short-chain alcohol as raw materials, reacts at a certain temperature and pressure, and obtains a nano-imbibition oil-displacing agent. Among them, citric acid, glucose and long-chain amine form amphiphilic carbon nanoparticles with hydrophilic groups and hydrophobic alkyl chains on the surface, and the ultra-small-sized amphiphilic carbon nanoparticles can significantly improve the efficiency of imbibition oil displacement by changing the wettability of the rock surface and reducing the oil-water interfacial tension. At the same time, the formed amphiphilic carbon nanoparticles form a synergistically stable nanoemulsion with the surfactant, organic solvent and short-chain alcohol, the surfactant can change the wettability of the rock, the organic solvent can improve the solubilization effect of the oil-displacing agent, and the short-chain alcohol can also increase the oil washing ability of the nanoemulsion while reducing the surface interfacial tension.

[0017] The preparation method of the invention is simple and convenient, environmentally friendly and low in cost. The prepared nano-imbibition oil displacement agent has good surface activity under high temperature and high salt conditions, can be used as an imbibition oil recovery agent in ultra-low permeability reservoirs, and can significantly improve crude oil recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the imbibition recovery curve of Example 1-2 and Comparative Example 1-2. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The raw materials used in the following examples are all commercially available products.

[0021] Example 1 1 g of citric acid, 2 g of glucose, 1 g of hexadecylamine, 6 g of lauryl amide propyl betaine, 4 g of xylene, 12 g of ethylene glycol and 74 g of distilled water were mixed evenly and placed in a sealed reactor for reaction at 140 °C and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain a nano-infiltration oil displacement agent.

[0022] Example 2 1 g of citric acid, 3 g of glucose, 2 g of dodecylamine, 7 g of cocamidopropyl betaine, 5 g of limonene, 14 g of isopropanol and 68 g of distilled water were mixed evenly and placed in a sealed reactor for reaction at 180 °C and 0.4 MPa for 12 hours. After the reaction was completed, the mixture was cooled to obtain a nano-infiltration oil displacement agent.

[0023] Example 3 0.5 g of citric acid, 0.5 g of glucose, 0.25 g of dodecylamine, 5 g of oleamidopropyl betaine, 3 g of limonene, 10 g of n-propanol and 80.75 g of water were mixed evenly and placed in a sealed reactor for reaction at 200 °C and 0.4 MPa for 6 hours. After the reaction was completed, the mixture was cooled to obtain a nano-infiltration oil displacement agent.

[0024] Example 4 2 g of citric acid, 4 g of glucose, 2 g of dodecylamine, 8 g of lauramide propyl hydroxysulfobetaine, 6 g of toluene, 15 g of propylene glycol and 73 g of water were mixed evenly and placed in a sealed reactor for reaction at 180 °C and 0.5 MPa for 12 hours. After the reaction was completed, the mixture was cooled to obtain a nano-infiltration oil displacement agent.

[0025] Example 5 2 g of citric acid, 4 g of glucose, 2 g of dodecylamine, 8 g of cocamidopropyl hydroxysulfobetaine, 6 g of toluene, 15 g of ethylene glycol and 73 g of water were mixed evenly and placed in a sealed reactor for reaction at 180 °C and 0.5 MPa for 12 hours. After the reaction was completed, the mixture was cooled to obtain a nano-infiltration oil displacement agent.

[0026] Comparative Example 1 A nano-infiltration oil-displacing agent, which is lauryl amide propyl betaine LAB-35, purchased from Linyi Lusen Chemical Co., Ltd.

[0027] Comparative Example 2 9 g of limonene, 18 g of isopropanol, 18 g of fatty alcohol polyoxyethylene ether AEO-9 and 55 g of KCl aqueous solution (concentration 50 g / L) were weighed respectively and mixed to prepare a nano-infiltration oil displacement agent.

[0028] Comparative Example 3 4 g of xylene, 12 g of ethylene glycol and 84 g of distilled water were mixed evenly and placed in a sealed reactor for reaction at 140 °C and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain an oil displacement agent.

[0029] Comparative Example 4 1 g of citric acid, 2 g of glucose, 1 g of hexadecylamine, 4 g of xylene, 12 g of ethylene glycol and 80 g of distilled water were mixed evenly and placed in a sealed reactor for reaction at 140 °C and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain a nano-infiltration oil displacement agent.

[0030] Comparative Example 5 1 g of citric acid, 2 g of glucose, 1 g of hexadecylamine, 6 g of lauryl amide propyl betaine, 12 g of ethylene glycol and 78 g of distilled water were mixed evenly and placed in a sealed reactor for reaction at 140 °C and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain a nano-infiltration oil displacement agent.

[0031] Comparative Example 6 1 g of citric acid, 2 g of glucose, 1 g of hexadecylamine, 12 g of ethylene glycol and 84 g of distilled water were mixed evenly and placed in a sealed reactor for reaction at 140 °C and 0.4 MPa for 16 hours. After the reaction was completed, the mixture was cooled to obtain a nano-infiltration oil displacement agent.

[0032] Performance Testing Interfacial tension test method: 1. Test instrument: TX-500C interfacial tension meter; 2. Test temperature: 60 ℃, 6,000 r / min; 3. Test oil phase: The oil phase is crude oil: diesel = 1:1, and the crude oil viscosity is 3 mPa‧s; 4. Test water: mineralization is 3% NaCl and 1% CaCl2.

[0033] 5. Test samples: The oil displacement agents prepared in Examples 1 to 5 and Comparative Examples 1 to 6 were respectively mixed with test water having a salinity of 3% NaCl and 1% CaCl2 to prepare test samples with a concentration of 0.5%.

[0034] Imbibition recovery test method: 1. Porosity: record the mass of the core dried to constant weight as m1, then saturate the core with distilled water, record the mass of the saturated core as m2, calculate the pore volume PV, PV=(m2-m1) / ρ; use a vernier caliper to measure the diameter and length of the core, calculate the volume of the core, and the ratio of the pore volume to the volume of the core is the porosity. The porosity of the core used in this application to test the imbibition recovery rate is 18%~20%.

[0035] 2. Determination of water permeability of core: Place the dried core in the core holder, inject distilled water into the core at an injection rate of 2 mL / min, stop the pump after the injection pressure stabilizes, and record the pressure difference at both ends of the core; use Darcy's formula to calculate the water permeability of the core. The water permeability of the core used in this application to test the imbibition recovery rate is (0.3~0.5)×10 -3 μm 2 .

[0036] 3. Saturation of core with crude oil: Use vacuum method to saturate with crude oil, place the dried core in the extraction device, connect the extraction device with the vacuum pump, open the oil suction valve, wait for the crude oil to immerse the core, close the oil suction valve, and maintain negative pressure for 4 hours. Place the saturated core in a 90℃ oven for aging for 12 hours.

[0037] 4. Static imbibition test method: The imbibition performance of the sample was evaluated by the amott method. The core and the imbibition liquid saturated with crude oil were placed in an amott bottle, the temperature of the imbibition liquid was maintained at 60°C, the volume of imbibition oil at different times was recorded, and the imbibition recovery rate was calculated. The concentration of the imbibition liquid was 500 mg / L, and the oil displacement agents prepared in Examples 1 to 5 and Comparative Examples 1 to 6 were mixed with test water having a salinity of 3% NaCl and 1% CaCl2.

[0038] Table 1 Imbibition recovery of different systems

[0039] Table 2 Interfacial tension of different systems before and after hot rolling

[0040] It can be seen from Table 1 and Table 2 that the nano-imbibition oil-displacing agent prepared in the embodiment of the present invention has a good imbibition recovery rate for crude oil, and the interfacial tension of the embodiment does not change much before and after hot rolling, which indicates that the nano-imbibition oil-displacing agent prepared in the embodiment has good temperature and salt resistance.

[0041] Compared with Comparative Example 1, the imbibition recovery rate, interfacial tension in brine and temperature resistance of the nano-imbibition oil-displacing agent in Example 1 are far superior to those of the existing amphoteric surfactants for imbibition oil-displacing; compared with Comparative Example 2, the imbibition recovery rate of the conventional nano-emulsion is lower than that of the nano-imbibition oil-displacing agent of the present invention, which is related to the magnitude of the interfacial tension; compared with Comparative Example 3, it can be seen that the amphiphilic carbon nanoparticles and the surfactant can significantly improve the imbibition recovery rate and reduce the interfacial tension; compared with Comparative Example 4, it is shown that the surfactant helps to form a nano-emulsion, which has a significant effect on improving the imbibition recovery rate and reducing the interfacial tension; compared with Comparative Example 5, it is shown that the organic solvent can help to improve the imbibition recovery rate, which is related to the solubilization effect of the organic solvent; compared with Comparative Example 6, it is shown that the organic solvent and the surfactant have a significant effect on improving the imbibition recovery rate and reducing the interfacial tension.

[0042] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For matters that are not described in detail in some embodiments, reference may be made to the description in other embodiments.

[0043] The above-mentioned embodiments only express the implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a nano-infiltration oil displacement agent, characterized in that: The following steps are involved: The nano-infiltration oil displacement agent is obtained by 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.

2. The preparation method of nano-infiltration oil displacement agent according to claim 1, characterized in that, In terms of 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.

3. The preparation method of nano-infiltration oil-displacing agent according to claim 1, characterized in that, The long-chain amine is a C8-C16 alkylamine.

4. The preparation method of nano-infiltration oil displacement agent according to claim 1, characterized in that, The surfactant is a betaine surfactant.

5. The preparation method of nano-infiltration oil-displacing agent according to claim 4, characterized in that, The betaine surfactant includes one or more of lauramidopropyl betaine, cocamidopropyl betaine, oleamidopropyl betaine, lauramidopropyl hydroxysulfobetaine, cocamidopropyl hydroxysulfobetaine, and oleamidopropyl hydroxysulfobetaine.

6. The preparation method of nano-infiltration oil displacement agent according to claim 1, characterized in that, The organic solvent is one or more of xylene, toluene and limonene.

7. The preparation method of nano-infiltration oil displacement agent according to claim 1, characterized in that, The short-chain alcohol is a C2~C6 alcohol.

8. The preparation method of the nano-infiltration oil-displacing agent according to claim 7, characterized in that, The short-chain alcohol is one or more of ethanol, isopropanol, n-propanol, ethylene glycol, and propylene glycol.

9. A nano-infiltration oil displacement agent, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. Use of the nano-imbibition oil-displacing agent prepared by the preparation method according to any one of claims 1 to 8 in oil displacement in low permeability reservoirs.

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