A temperature-resistant and salt-resistant polyether sulfonate oil-displacing agent and its preparation method

Abstract

The present invention relates to the technical field of oil displacement agents, and particularly to a temperature- and salt-resistant polyether sulfonate oil displacement agent and a preparation method thereof. By compounding amphiphilic FAU nanocrystals with polyether sulfonates, the temperature- and salt-resistance is enhanced. This compound system has good emulsifying ability, dispersion stability and mobility control ability, and can significantly improve the oil recovery rate. Hydrophobically modified FAU zeolite enhances the oil-phase affinity, improves the oil displacement efficiency, and reduces the impact on the environment at the same time. This system is biodegradable, meets the requirements of environmental protection and sustainable development, and provides a new solution for oilfield chemical flooding technology.

Description

Technical Field

[0001] The present invention relates to the technical field of oil displacement agents, and particularly relates to a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent and a preparation method thereof. Background Art

[0002] Petroleum is known as the "blood of industry" and occupies a major part of the energy used by humans, having extremely important strategic significance. After most oil fields go through the secondary oil recovery water injection stage, the oil recovery rate is less than 50% (Du Chunbao, Cai Yuxiu, Yan Yongli, etc. Research progress of new chemical oil displacement technologies [J]. Modern Chemical Industry, 2022, 42(6): 35-39.). A large amount of crude oil still remains in the underground reservoir, and it has become very difficult to displace this part of the crude oil by water injection. Moreover, the situation of tight petroleum resources is becoming increasingly severe. Improving the crude oil recovery rate is an urgent problem to be solved currently. Improving the recovery rate is also known as tertiary oil recovery, which is divided into chemical flooding, miscible flooding, thermal recovery, and microbial flooding, etc. Among them, chemical flooding has the most mature application and broad development prospects. Chemical flooding refers to adding a certain amount of chemical reagents to the injection fluid. Common chemical floods can be divided into: polymer flooding, surfactant flooding, and composite flooding, etc. Polymer flooding is outstanding in improving the mobility ratio and profile control, and is the most widely used. However, it is difficult to simultaneously possess excellent properties such as temperature and salt resistance and improving the mobility ratio during the synthesis of polymers; surfactant flooding improves the crude oil recovery rate by reducing the interfacial tension and changing the wettability, but the surfactant has a low sweep efficiency and large adsorption losses; composite flooding can synergistically combine the oil displacement mechanisms of polymers and surfactants, with high displacement efficiency but chromatographic separation phenomenon, which affects the oil production efficiency. To sum up, the currently large-scale applied chemical floods all have certain defects, which limit the on-site application of chemical floods. There is an urgent need to study new technologies to improve the oil recovery rate.

[0003] The units of the nanoparticle composition are small in size, with high surface activity and a large specific surface area. Laboratory studies have proven that nanomaterials have the ability to improve oil recovery when used in enhanced oil recovery. Nanoparticles can be dispersed in water or an oil-water mixed system to drive oil alone, or can be used in combination with surfactants or polymers. The preparation process of nanomaterials is complex and the productivity is low, making it difficult to apply industrially. Moreover, when nanoparticles are used in combination with surfactants, challenges related to dispersion and stability also arise. In the composite system, the interaction between nanoparticles and surfactants may lead to complex changes in surface activity, viscosity, and conductivity, affecting the performance of the system. The adsorption arrangement law of nanoparticles at the gas-liquid interface and the influence of surfactants on their adsorption law are key factors. The adsorption process of nanoparticles needs to overcome a certain adsorption energy barrier, such as electrostatic repulsion. In addition, the irreversible adsorption characteristics of nanoparticles result in an increase in adsorption density during the droplet shrinkage process, thus affecting surface tension and foam stability. The addition of surfactants will change the wettability of nanoparticles, and thus affect their adsorption behavior at the gas-liquid interface, which is crucial for the stability of foams or emulsions. However, the current complex preparation methods and low yields of nanoparticles also restrict their development in the field of oil displacement agents. Summary of the Invention

[0004] The purpose of the present invention is to provide a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent and its preparation method. By preparing amphiphilic FAU nanocrystals, it has a more stable dispersion ability. The nanofluid dispersed by amphiphilic FAU nanocrystals has long-term stability. Compared with nanoparticles modified by a single functional group, it has a large specific surface area and stronger abilities such as reducing interfacial tension and changing the wettability of reservoir rock surfaces, and has high application potential in improving crude oil recovery. The lipophilic FAU nanocrystals prepared by the one-step method of the present invention have high crystallinity, good dispersion, and high yield, and the amphiphilic FAU nanocrystals prepared on this basis still maintain a stable crystal structure. By finely regulating the ratio and interaction when the amphiphilic FAU nanocrystals are used in combination with polyether sulfonate, the performance of the system is optimized, and its temperature-resistant and salt-resistant performance is further improved.

[0005] To solve the above technical problems, the present invention provides a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent and its preparation method.

[0006] To achieve the above object, the present invention provides the following technical solution: A temperature-resistant and salt-resistant polyether sulfonate oil displacement agent and its preparation method, including the following steps:

[0007] Step 1: Add a silane hydrophobic template agent to silica white and mix evenly. Then add an aqueous sodium aluminate solution prepared by dissolving sodium aluminate in water, and stir evenly to obtain a gel-like semi-liquid mixture, where the above raw materials are in a mass ratio of silica white:sodium aluminate:silane hydrophobic template agent:water = 1:0.5 - 2:0.8 - 2:5 - 15;

[0008] Step 2: Under the condition of steam assistance, subject the above mixture to crystallization treatment to obtain a crystalline product;

[0009] Step 3: Subject the crystalline product to washing, drying and calcination treatment in sequence to obtain lipophilic FAU nanocrystals by a one-step method;

[0010] Step 4: Put an aqueous sodium hydroxide solution (concentration 1 - 10 g / L) into a round-bottom flask, add ethanol and mix evenly, add lipophilic FAU nanocrystals, and stir at 70 - 100 °C for 2 - 5 hours to obtain an amphiphilic FAU nanocrystal fluid. In terms of mass ratio of the above raw materials, lipophilic FAU nanocrystals: aqueous sodium hydroxide solution: ethanol = 1:60 - 100:10 - 25;

[0011] Step 5: Add the amphiphilic FAU nanocrystal fluid, polyether sulfonate and water into a round-bottom flask and stir at 70 - 80 °C for 2 - 5 hours to prepare a temperature- and salt-resistant polyether sulfonate oil displacement agent. In terms of mass ratio of the above raw materials, amphiphilic FAU nanocrystal fluid: polyether sulfonate: water = 100:1.5 - 20:0.5 - 200.

[0012] Further, the silane hydrophobic template agent is one of 3-aminopropyltriethoxysilane and (3-(2-aminoethyl)aminopropyl)triethoxysilane.

[0013] Further, the polyether sulfonate is one of sodium octylphenol polyoxyethylene ether sulfonate and disodium lauryl alcohol polyoxyethylene ether sulfosuccinate.

[0014] Further, under the condition of steam assistance in Step 2, subjecting the mixture to crystallization treatment specifically includes the following steps: Transfer the mixture into an open glassware, then transfer the glassware into the liner of a hydrothermal reaction kettle. Add deionized water into the liner, and its mass is 0.5 - 2 times the mass of the mixture, and prevent the water outside the glassware from entering the glassware; Under the condition of steam assistance at a temperature of 60 - 100 °C, subject the mixture to crystallization treatment, and the crystallization time is 6 - 12 hours.

[0015] Further, the calcination temperature in Step 3 is 120 - 300 °C, and the calcination time is 3 - 6 hours.

[0016] A temperature-resistant and salt-resistant polyether sulfonate oil displacement agent provided by the present invention and its preparation method realize a significant improvement in the temperature resistance and salt resistance of polyether sulfonate by compounding amphiphilic FAU nanocrystals with polyether sulfonate. In the preparation process, we adopted a one-step method to directly synthesize highly productive lipophilic FAU nanocrystals, and on this basis, prepared FAU nanocrystal fluids with amphiphilic properties without destroying the crystal structure. Such amphiphilic FAU nanocrystal fluids can form a stable adsorption layer at the oil-water interface, enhance the strength of the droplet interfacial film, and improve the interfacial viscoelasticity of the emulsion. At the same time, its amphiphilic properties also help to construct a three-dimensional network structure in the bulk phase, enhance the bulk viscosity of the emulsifying oil displacement system, effectively delay the coalescence of emulsion droplets, and greatly improve the stability of the emulsion. As a surfactant, polyether sulfonate not only further enhances this stability, but also significantly improves the salt resistance and high-temperature resistance of the oil displacement agent due to its strong hydrophilicity. This compound system, with its excellent emulsifying ability, good dispersion stability, and enhanced mobility control ability, is beneficial to improving the sweep efficiency, thereby significantly enhancing the oil recovery rate. After the hydrophobic modification of FAU zeolite, its surface properties are adjusted, enhancing the affinity with the oil phase and playing a greater role in the oil displacement process. This modified zeolite can more effectively adsorb and transfer oil molecules while reducing the flow resistance of the aqueous phase, further improving the oil displacement efficiency. The combination of polyether sulfonate and hydrophobic modified FAU zeolite not only improves the performance of the oil displacement agent in the reservoir, but also reduces the impact on the ecological environment due to its environmental friendliness. The biodegradability of this compound system and its low interference with the reservoir environment make it meet the requirements of environmental protection and sustainable development in modern oilfield development while increasing the oil recovery rate. Therefore, the synergistic effect of polyether sulfonate and hydrophobic modified FAU zeolite not only shows high efficiency technically, but also shows its important value in saving resources and protecting the environment, providing new ideas and solutions for the development of oilfield chemical oil displacement technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 XRD pattern of the temperature-resistant and salt-resistant polyether sulfonate oil displacement agent prepared in Example 1 of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0019] The following specifically describes a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent provided by the present invention and its preparation method through examples.

[0020] Example 1

[0021] Step 1: Add 3-aminopropyltriethoxysilane to fumed silica and mix evenly. Add an aqueous solution of sodium aluminate prepared by dissolving sodium aluminate in water. After stirring evenly, a gel-like semi-liquid mixture is obtained. Among the above raw materials, the mass ratio of fumed silica:sodium aluminate:3-aminopropyltriethoxysilane:water = 1:0.95:1:5;

[0022] Step 2: Under the condition of steam assistance, transfer the above mixture into an open glassware, and then transfer the glassware into the liner of a hydrothermal reaction kettle. Add deionized water to the liner, and its mass is 1 time that of the mixture. Also, prevent the water outside the glassware from entering the glassware. At a temperature of 85 °C and under the condition of steam assistance, carry out crystallization treatment on the mixture for 10 hours to obtain a crystalline product;

[0023] Step 3: Wash, dry, and calcine the crystalline product in sequence. The calcination temperature is 250 °C and the calcination time is 5 hours. The lipophilic FAU nanocrystals are prepared in one step;

[0024] Step 4: Put an aqueous sodium hydroxide solution (concentration 1.25 g / L) into a round-bottom flask, add ethanol and mix evenly, add lipophilic FAU nanocrystals, and stir at 85 °C for 3 hours to obtain an amphiphilic FAU nanocrystal fluid. Among the above raw materials, the mass ratio of lipophilic FAU nanocrystals:aqueous sodium hydroxide solution:ethanol = 1:80:19;

[0025] Step 5: Add the amphiphilic FAU nanocrystal fluid, sodium octylphenol polyoxyethylene ether sulfonate, and water to a round-bottom flask and stir at 80 °C for 3 hours to prepare a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent. Among the above raw materials, the mass ratio of amphiphilic FAU nanocrystal fluid:sodium octylphenol polyoxyethylene ether sulfonate:water = 100:2.5:1.

[0026] Filter and dry the amphiphilic FAU nanocrystal fluid prepared in Step 4 to prepare amphiphilic FAU nanocrystals for XRD testing as Figure 1 shown. The product has good crystallization, no amorphous phase, shows the first peak at 6.09°, and the remaining peak positions all correspond to PDF#12-0246 in jade, proving that the sample is FAU zeolite.

[0027] Example 2

[0028] Step 1: Add 3-aminopropyltriethoxysilane to fumed silica and mix evenly. Then add an aqueous solution of sodium aluminate prepared by dissolving sodium aluminate in water. After stirring evenly, a gel-like semi-liquid mixture is obtained, where the above raw materials are in a mass ratio of fumed silica:sodium aluminate:3-aminopropyltriethoxysilane:water = 1:1.25:1.1:1;

[0029] Step 2: Under the condition of steam assistance, transfer the above mixture into an open glassware, and then transfer the glassware into the liner of a hydrothermal reactor. Add deionized water to the liner, and its mass is 1 times that of the mixture. Also, prevent the water outside the glassware from entering the glassware. At a temperature of 90 °C and under the condition of steam assistance, carry out crystallization treatment on the mixture for 8 hours to obtain a crystalline product;

[0030] Step 3: Wash, dry, and calcine the crystalline product in sequence. The calcination temperature is 250 °C and the calcination time is 5 hours to obtain lipophilic FAU nanocrystals by a one-step method;

[0031] Step 4: Put an aqueous sodium hydroxide solution (concentration 1.53 g / L) into a round-bottom flask, add ethanol and mix evenly, then add lipophilic FAU nanocrystals, and stir at 75 °C for 3 hours to obtain an amphiphilic FAU nanocrystal fluid. The above raw materials are in a mass ratio of lipophilic FAU nanocrystals:aqueous sodium hydroxide solution:ethanol = 1:70:29;

[0032] Step 5: Add the amphiphilic FAU nanocrystal fluid, sodium octylphenol polyoxyethylene ether sulfonate, and water into a round-bottom flask and stir at 85 °C for 3 hours to prepare a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent. The above raw materials are in a mass ratio of amphiphilic FAU nanocrystal fluid:sodium octylphenol polyoxyethylene ether sulfonate:water = 100:1.5:10.

[0033] Example 3

[0034] Step 1: Add (3-(2-aminoethyl)aminopropyl)triethoxysilane to fumed silica and mix evenly. Then add an aqueous solution of sodium aluminate prepared by dissolving sodium aluminate in water. After stirring evenly, a gel-like semi-liquid mixture is obtained, where the above raw materials are in a mass ratio of fumed silica:sodium aluminate:(3-(2-aminoethyl)aminopropyl)triethoxysilane:water = 1:1.1:2:10;

[0035] Step 2: Under the condition of steam assistance, transfer the above mixture into an open glassware, and then transfer the glassware into the liner of a hydrothermal reactor. Add deionized water to the liner, and its mass is 1 times that of the mixture. Also, prevent the water outside the glassware from entering the glassware. At a temperature of 100 °C and under the condition of steam assistance, carry out crystallization treatment on the mixture for 6 hours to obtain a crystalline product;

[0036] Step 3: Wash, dry, and calcine the crystallization product successively. The calcination temperature is 250 °C and the calcination time is 5 hours to obtain lipophilic FAU nanocrystals by a one-step method.

[0037] Step 4: Put an aqueous sodium hydroxide solution (concentration 1.7 g / L) into a round-bottom flask, add ethanol and mix evenly, then add lipophilic FAU nanocrystals and stir at 75 °C for 3 hours to obtain an amphiphilic FAU nanocrystal fluid. In terms of mass ratio, the raw materials are as follows: lipophilic FAU nanocrystals: aqueous sodium hydroxide solution: ethanol = 1:65:34.

[0038] Step 5: Add the amphiphilic FAU nanocrystal fluid, sodium lauryl polyoxyethylene ether sulfosuccinate, and water into a round-bottom flask and stir at 85 °C for 3 hours to prepare a temperature- and salt-resistant polyether sulfonate oil-displacing agent. In terms of mass ratio, the raw materials are as follows: amphiphilic FAU nanocrystal fluid: sodium lauryl polyoxyethylene ether sulfosuccinate: water = 100:3:100.

[0039] Comparative Example 1:

[0040] Step 1: Put an aqueous sodium hydroxide solution (concentration 1.25 g / L) into a round-bottom flask, add ethanol and mix evenly, then add sodium octylphenol polyoxyethylene ether sulfate and stir at 85 °C for 10 minutes. In terms of mass ratio, the raw materials are as follows: aqueous sodium hydroxide solution: ethanol = 80:20.

[0041] Step 2: Add the mixture prepared in Step 1, sodium octylphenol polyoxyethylene ether sulfate, and water into a round-bottom flask and stir at 80 °C for 3 hours. In terms of mass ratio, the raw materials are as follows: mixture: sodium octylphenol polyoxyethylene ether sulfate: water = 100:2.5:1.

[0042] The salt resistance of Example 1 and Comparative Example 1 was observed by testing the solubility of the oil-displacing agent after standing at 25 °C for 24 hours with different NaCl contents, as shown in Table 1.

[0043] Table 1

[0044] The temperature resistance of Example 1 and Comparative Example 1 was evaluated by examining the influence of the temperature resistance of the oil-displacing agent under the condition of 270 °C, as shown in Table 2. The initial concentration was based on sodium octylphenol polyoxyethylene ether sulfate. It was added to a reaction kettle, heated to 270 °C under closed conditions, maintained for different times, and the active substance content was detected by two-phase titration.

[0045] Table 2

[0046] Summary: As can be seen from Table 1 and Table 2, the oil displacement agent prepared by combining amphiphilic FAU nanocrystal fluid with polyether sulfonate in Example 1 is superior to ordinary polyether sulfonate in terms of temperature resistance and salt resistance, etc.

[0047] Finally, it should be noted that the above specific embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the examples, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A preparation method of a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent, characterized in that, It includes the following steps: Step 1: Add a silane hydrophobic templating agent to silica white and mix evenly. Then add an aqueous solution of sodium aluminate prepared by dissolving sodium aluminate in water. After stirring evenly, a gel-like semi-liquid mixture is obtained. The mass ratio of the above raw materials is silica white:sodium aluminate:silane hydrophobic templating agent:water = 1:0.5 - 2:0.8 - 2:5 - 15; Step 2: Under the condition of steam assistance, perform crystallization treatment on the above mixture to obtain a crystalline product; Step 3: Subject the crystalline product to washing, drying and calcination treatment in sequence to obtain lipophilic FAU nanocrystals by a one-step method; Step 4: Put an aqueous sodium hydroxide solution with a concentration of 1 - 10 g / L into a round-bottom flask, add ethanol and mix evenly. Then add lipophilic FAU nanocrystals and stir at 70 - 100 °C for 2 - 5 hours to obtain an amphiphilic FAU nanocrystal fluid. The mass ratio of the above raw materials is lipophilic FAU nanocrystals:aqueous sodium hydroxide solution:ethanol = 1:60 - 100:10 - 25; Step 5: Add the amphiphilic FAU nanocrystal fluid, polyether sulfonate and water to a round-bottom flask and stir at 70 - 80 °C for 2 - 5 hours to obtain a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent. The mass ratio of the above raw materials is amphiphilic FAU nanocrystal fluid:polyether sulfonate:water = 100:1.5 - 20:0.5 - 200; The calcination temperature in Step 3 is 120 - 300 °C and the calcination time is 3 - 6 hours.

2. The preparation method of a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent according to claim 1, characterized in that, The silane hydrophobic templating agent is one of 3-aminopropyltriethoxysilane and (3-(2-aminoethyl)aminopropyl)triethoxysilane.

3. The preparation method of a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent according to claim 1, characterized in that, The polyether sulfonate is one of sodium octylphenol polyoxyethylene ether sulfonate and disodium lauryl alcohol polyoxyethylene ether sulfosuccinate.

4. The preparation method of a temperature-resistant and salt-resistant polyether sulfonate oil displacement agent according to claim 3, characterized in that, Under the condition of steam assistance in Step 2, the crystallization treatment of the mixture specifically includes the following steps: Transfer the mixture into an open glassware, and then transfer the glassware into the liner of a hydrothermal reaction kettle. Add deionized water to the liner, and its mass is 0.5 - 2 times the mass of the mixture, and prevent the water outside the glassware from entering the glassware. Under the condition of steam assistance at a temperature of 60 - 100 °C, perform crystallization treatment on the mixture, and the crystallization time is 6 - 12 hours.

5. A temperature-resistant and salt-resistant polyether sulfonate oil-displacing agent, characterized in that, It is prepared by the method described in any one of claims 1 - 4.

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