A synergistic supramolecular inclusion polymer oil displacement system, and a preparation method and application thereof

Abstract

The application provides a synergistic supramolecular inclusion polymer oil displacement system and a preparation method and application thereof. The synergistic supramolecular inclusion polymer oil displacement system comprises the following raw materials: a host polymer, a guest amphiphilic polymer, an amphoteric surfactant and mineralized water; the host polymer is a beta-cyclodextrin polymer; the guest amphiphilic polymer is a salt-tolerant adamantyl amphiphilic polymer; and the amphoteric surfactant is selected from betaine type amphoteric surfactants. The application takes specific types of host polymers, specific types of guest amphiphilic polymers and specific types of surfactants as building units, forms a synergistic supramolecular inclusion polymer oil displacement system through host-guest inclusion and electrostatic interaction and other non-covalent bond forces, can reduce the polymer use concentration and cost, and has the performances of high viscosity and ultra-low interfacial tension, can effectively improve the oil recovery ratio by improving the sweep volume and oil washing efficiency.

Description

Technical Field

[0001] This invention relates to an enhanced supramolecular inclusion polymer flooding system, its preparation method and application, belonging to the field of tertiary oil recovery technology. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Chemical flooding is the main enhanced oil recovery (EOR) method used in my country. Chemical flooding technology has developed rapidly in my country, with polymer flooding technology already achieving industrial application. In Daqing Oilfield alone, it can increase crude oil production by more than 12 million tons annually. As oilfield development continues, high-temperature, high-salinity reservoirs are gradually becoming the focus of development. However, under high-salinity conditions, due to the electrostatic shielding effect of salt, the viscosity of polymers decreases significantly, and the mobility control capability cannot meet the requirements of polymer flooding, seriously affecting its effectiveness.

[0004] Amphiphilic polymers contain a small number of hydrophobic groups in their molecular chains. When dissolved in water, these hydrophobic groups associate to form supramolecular aggregates, resulting in a reversible network structure and a significant increase in solution viscosity. This gives amphiphilic polymers rheological properties different from those of typical water-soluble polymers. However, as research on amphiphilic polymers deepens, their limitations have gradually become apparent. Amphiphilic polymer aqueous solutions exhibit a critical aggregation concentration (CAC). Above the CAC, the hydrophobic groups associate to form aggregate structures, leading to an increase in hydrodynamic volume and thus producing good viscosity-enhancing properties. However, when the concentration is below the CAC, the viscosity-enhancing effect is greatly limited.

[0005] In recent years, non-covalent interactions have been widely applied in oilfield development. Based on supramolecular inclusion interactions, the introduction of cyclodextrins into amphiphilic polymer systems to construct supramolecular systems can not only improve the system's temperature and salt resistance to a certain extent, but also achieve the goal of low concentration and high viscosity, showing great application potential and value in tertiary oil recovery. However, the current supramolecular inclusion polymer flooding system still needs to reduce its application cost, and its ability to reduce oil-water interfacial tension is limited, which is not conducive to improving oil washing efficiency and crude oil recovery during the flooding process. For example, Chinese patent document CN104861950A discloses a supramolecular linear polyacrylamide flooding agent, composed of the following components: adamantane-terminated polyacrylamide, β-cyclodextrin dimer, additives, oxygen scavenger, and water. The flooding agent prepared by this invention has viscosity that is less affected by molecular weight and is adjustable; the supramolecular polyacrylamide molecular chain is linear, and its solubility is good; this flooding agent also has better anti-aging ability. However, the effect of this oil displacement agent in reducing oil-water interfacial tension is not disclosed, and its temperature resistance, high salinity resistance, and oil recovery enhancement effects need further improvement. Existing technologies also report on supramolecular oil displacement systems composed of amphoteric surfactants in conjunction with other surfactants. For example, Chinese patent document CN113150762A discloses a supramolecular oil displacement system and its application that combines viscoelasticity and ultra-low interfacial tension, and for the first time combines anionic surfactants, betaine-type amphoteric surfactants, and water to form an oil displacement system. The oil displacement system used in this invention possesses both the high viscoelasticity of polymer systems and the ability to form ultra-low interfacial tension with crude oil. This supramolecular oil displacement system composed of anionic surfactants / betaine-type amphoteric surfactants can further enhance oil recovery. However, under high temperature and high salinity conditions, the viscoelasticity of this oil displacement system is greatly reduced, severely affecting its ability to expand the swept volume and enhance oil recovery. Summary of the Invention

[0006] To address the problems of high cost, limited ability to reduce oil-water interfacial tension, low oil washing efficiency, and unsatisfactory oil recovery effects in existing oil displacement systems, this invention provides an enhanced supramolecular inclusion polymer oil displacement system, its preparation method, and its application. More specifically, it is an enhanced supramolecular inclusion polymer oil displacement system with ultra-low interfacial tension, its preparation method, and its application. Using specific types of host polymers, specific types of guest amphiphilic polymers, and specific types of surfactants as building blocks, the enhanced supramolecular inclusion polymer oil displacement system is formed through non-covalent interactions such as host-guest inclusion and electrostatic interactions. This system reduces polymer concentration and cost while simultaneously possessing high viscosity and ultra-low interfacial tension, effectively improving oil recovery by increasing both swept volume and oil washing efficiency.

[0007] This invention is achieved through the following technical solution:

[0008] An enhanced supramolecular inclusion polymer oil displacement system comprises the following raw materials: a host polymer, a guest amphiphilic polymer, an amphoteric surfactant, and mineralized water; wherein the host polymer is a β-cyclodextrin polymer; the guest amphiphilic polymer is a salt-resistant adamantyl amphiphilic polymer; and the amphoteric surfactant is selected from betaine-type amphoteric surfactants.

[0009] According to the present invention, the β-cyclodextrin polymer P(AM / AMPS / A-β-CD) has the following structure:

[0010]

[0011] Where a:b:c = 30-36:4-10:1.

[0012] According to a preferred embodiment of the present invention, the preparation method of β-cyclodextrin polymer includes the following steps: dissolving acrylamide, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and allyl-β-cyclodextrin (A-β-CD) in distilled water, adding NaOH to adjust the pH of the system to neutral, then adding the initiator azobisisobutyramidine hydrochloride (AIBA), reacting, and then pulverizing, washing and drying to obtain β-cyclodextrin polymer.

[0013] Preferably, the molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and allyl-β-cyclodextrin (A-β-CD) is 30-36:4-10:1, and more preferably 31.9:8:1.

[0014] Preferably, the mass ratio of the total mass of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and allyl-β-cyclodextrin (A-β-CD) monomers to distilled water is 0.1-0.5:1, more preferably 0.25:1.

[0015] Preferably, the mass of the initiator azobisisobutyramidine hydrochloride is 0.02%-0.05% of the total mass of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and allyl-β-cyclodextrin (A-β-CD) monomers.

[0016] Preferably, the reaction temperature is 38-45℃, the reaction time is 2-6h, and the reaction is carried out under nitrogen or argon protection.

[0017] According to the present invention, the salt-resistant adamantyl alkyl amphiphilic polymer (P(AM / MAPS / N-ADA)) has the following structure:

[0018]

[0019] Where x:y:z = 35-40:0.8-2:1.

[0020] According to a preferred embodiment of the present invention, the preparation method of the salt-resistant adamantyl amphiphilic polymer includes the following steps: dissolving acrylamide, salt-resistant monomer MAPS (sodium 3-(N-allyl-N-methylamino)propane-1-sulfonate), and acrylamide-adamantane in distilled water, adding ammonium persulfate and sodium bisulfite, reacting, and then pulverizing, washing, and drying to obtain the salt-resistant adamantyl amphiphilic polymer.

[0021] According to the present invention, the structural formulas of the salt-tolerant monomer MAPS and acrylamide-adamantane are as follows, and the salt-tolerant monomer MAPS can be prepared by existing methods:

[0022]

[0023] Preferably, the molar ratio of acrylamide, salt-resistant monomer MAPS, and acrylamide-adamantane is 35-40:0.8-2:1, and more preferably 38.7:1.2:1.

[0024] Preferably, the mass ratio of acrylamide, salt-resistant monomer MAPS, acrylamide-adamantane monomer, and distilled water is 0.1-0.5:1, more preferably 0.25:1.

[0025] Preferably, the mass ratio of ammonium persulfate to sodium bisulfite is 2-4:1; the total mass of ammonium persulfate and sodium bisulfite is 0.1-0.3% of the total mass of acrylamide, salt-tolerant monomer MAPS, and acrylamide-adamantane monomer.

[0026] Preferably, the reaction temperature is 25-35℃, the reaction time is 2-6h, and the reaction is carried out under nitrogen or argon protection.

[0027] According to a preferred embodiment of the present invention, the viscosity-average molecular weight of the host polymer and the guest amphiphilic polymer is 4 × 10⁻⁶. 6 ~2×10 7 .

[0028] According to a preferred embodiment of the present invention, the amphoteric surfactant is erucamide propyl betaine or erucamide propyl hydroxysulfonamide betaine.

[0029] According to a preferred embodiment of the present invention, the mineralization degree of the mineralized water is 1000 mg / L to 100000 mg / L.

[0030] According to a preferred embodiment of the present invention, the mass ratio of the host polymer, the guest amphiphilic polymer, the amphoteric surfactant, and the mineralized water is 1-5:1-5:0.5-2:800-1200, preferably 2:2:1:1000.

[0031] The preparation method of the above-mentioned enhanced supramolecular inclusion polymer oil displacement system includes the following steps: dissolving an amphoteric surfactant in mineralized water; adding a host polymer and a guest amphiphilic polymer and dispersing them fully; and then allowing them to stand and mature to obtain the enhanced supramolecular inclusion polymer oil displacement system.

[0032] According to a preferred embodiment of the present invention, the amphoteric surfactant is added to the mineralized water and stirred at room temperature for 10 to 30 minutes to ensure that the amphoteric surfactant is fully dissolved in the mineralized water; preferably, the stirring time is 20 to 30 minutes.

[0033] According to the present invention, full dispersion is achieved by stirring at room temperature for 1 to 3 hours; preferably, the stirring time at room temperature is 2 hours.

[0034] According to the present invention, the static curing temperature is 40-60℃ and the static curing time is 20-30 hours; more preferably, the static curing temperature is 50℃ and the static curing time is 24 hours.

[0035] The aforementioned enhanced supramolecular inclusion polymer enhanced oil recovery system is applied to tertiary oil recovery in oil fields to improve crude oil recovery rate.

[0036] The technical features and beneficial effects of this invention are as follows:

[0037] 1. This invention uses a host polymer, a guest amphiphilic polymer, and a surfactant as building blocks. In the presence of mineralized water, it forms an enhanced supramolecular inclusion polymer oil displacement system through non-covalent inclusion forces and electrostatic interactions. Compared to existing hydrophobic association, the host-guest inclusion forces are stronger. The polymer molecular spatial network structure formed by the cyclodextrin groups on the host polymer and the hydrophobic groups on the guest polymer is more compact, resulting in better viscosity enhancement and shear resistance. Simultaneously, the cationic groups on the amphoteric surfactant and the negatively charged groups on the guest amphiphilic polymer molecular chains are connected through electrostatic interactions, further improving the spatial network structure strength and viscosity of the polymer oil displacement system. Furthermore, because the amphoteric surfactant molecules possess amphiphilic groups, being both hydrophilic and lipophilic, they also endow the oil displacement system with excellent ability to reduce oil-water interfacial tension.

[0038] 2. The main polymer of this invention must be a β-cyclodextrin polymer with a specific structure, and the guest amphiphilic polymer must be a salt-resistant adamantyl amphiphilic polymer with a specific structure. β-cyclodextrin is inexpensive, readily available, and easily modified; furthermore, the hydrophobic cavity of this type of polymer has good compatibility with the hydrophobic adamantyl group of the guest polymer of this invention, resulting in the highest binding constant and the strongest inclusion force; the salt-resistant adamantyl amphiphilic polymer used in this invention, when compounded with the β-cyclodextrin polymer, can achieve the goal of low concentration and high viscosity, thereby reducing costs while improving oil recovery. The unique structure of the salt-resistant adamantyl amphiphilic polymer of this invention significantly improves the salt resistance of the oil displacement system and can form a low-concentration, high-viscosity inclusion system with the β-cyclodextrin polymer; if the salt-resistant group (MAPS) is omitted, the system is not salt-resistant; if the adamantyl group is omitted, it is impossible to form a low-concentration, high-viscosity inclusion system with the β-cyclodextrin polymer; and using other types of guest amphiphilic polymers or changing the structure of the guest amphiphilic polymers will not achieve the excellent effects of this invention. If the β-cyclodextrin polymer of this invention is replaced with other types of cyclodextrin polymers (α-cyclodextrin polymers or γ-cyclodextrin polymers) or the structure of the cyclodextrin polymer is changed, the excellent effects of this invention will not be achieved, and the effects of thickening and improving oil recovery will be reduced.

[0039] 3. The amphoteric surfactant of this invention is a betaine-type amphoteric surfactant. This type of surfactant can not only increase the viscosity of the system but also reduce the interfacial tension of the system to ultra-low levels. Commonly used amphoteric surfactants can only slightly reduce the interfacial tension of the system and cannot increase the viscosity.

[0040] 4. The ratio of each raw material in this invention is optimal. Under this ratio, not only is the viscosity highest, the interfacial tension lowest, and a high oil recovery rate achieved, but the amount of raw materials used in the system is also minimal. If the ratio is not appropriate, this optimal effect cannot be achieved.

[0041] 5. The oil displacement system of this invention consists of raw materials as a whole, which works together to successfully solve the problem of high concentration of amphiphilic polymers. It has good viscosity-enhancing properties at low concentrations, and the oil displacement system has good shear resistance and can effectively reduce the interfacial tension between oil and water. During the oil displacement process, it can effectively reduce the water-oil mobility ratio, avoid the viscous fingering phenomenon in water flooding, increase the swept volume, and effectively improve the oil washing efficiency, thereby significantly improving the recovery rate.

[0042] 6. The oil displacement system construction method of the present invention is simple, easy to operate, uses low polymer concentration, has low cost, high oil displacement efficiency, strong practicality, and is easy to promote. Attached Figure Description

[0043] Figure 1 The image shows the enhanced oil recovery effect of the synergistic supramolecular inclusion polymer enhanced oil recovery system prepared in Example 1.

[0044] Figure 2 The graph shows the change in water content at the outlet end during the oil displacement process of the enhanced supramolecular inclusion polymer oil displacement system prepared in Example 1.

[0045] Figure 3 The diagram shows the effect of the enhanced supramolecular inclusion polymer oil displacement system prepared in Example 1 on reducing the oil-water interfacial tension. Detailed Implementation

[0046] It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless specific conditions are specified, are generally performed under conventional conditions or as recommended by the manufacturer. The following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0047] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this disclosure.

[0048] The present invention will be further described below with reference to specific embodiments.

[0049] Example 1

[0050] An enhanced supramolecular inclusion polymer oil displacement system comprises the following raw material components by weight: 2g of β-cyclodextrin polymer, 2g of salt-resistant adamantyl amphiphilic polymer (P(AM / MAPS / N-ADA)), 1g of amphoteric surfactant erucamide propyl betaine, and 1000g of mineralized water with a mineralization degree of 32868mg / L.

[0051] The preparation method of β-cyclodextrin polymer P (AM / AMPS / A-β-CD) includes the following steps: 0.7975 mol acrylamide, 0.2 mol 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and 0.025 mol allyl-β-cyclodextrin (A-β-CD) are added to a beaker containing distilled water, wherein the total monomer concentration is 25 wt%, and the molar ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and allyl-β-cyclodextrin (A-β-CD) is 31.9:8:1. After stirring until completely dissolved, solid NaOH is added to adjust the pH of the solution to neutral. The solution was transferred to a three-necked flask and heated to 42°C in a constant-temperature water bath. Nitrogen gas was bubbled into the flask for 0.5 hours to purge oxygen from the solution and the flask. Then, 0.04% (by mass) of the initiator azobisisobutyramidine hydrochloride (AIBA) was added, and the reaction was carried out under nitrogen for 4 hours to synthesize a polymer block. This block was sheared and pulverized, washed three times with ethanol, and then dried in a vacuum drying oven to constant weight to obtain the target product, β-cyclodextrin polymer P (AM / AMPS / A-β-CD), with a viscosity-average molecular weight of 8.5 million.

[0052] The preparation method of the salt-resistant adamantane amphiphilic polymer (P(AM / MAPS / N-ADA)) includes the following steps: 0.9675 mol acrylamide, 0.03 mol salt-resistant monomer MAPS, and 0.025 mol acrylamide-adamantane monomer are added to a three-necked flask containing distilled water, wherein the total monomer concentration is 25 wt%, and the molar ratio of acrylamide, salt-resistant monomer MAPS, and acrylamide-adamantane monomer is 38.7:1.2:1; after complete dissolution, nitrogen gas is purged into the three-necked flask for 0.5 h to purge air. Then, ammonium persulfate and sodium bisulfite (mass ratio of ammonium persulfate to sodium bisulfite is 3:1), accounting for 0.1% of the total monomer mass fraction, are added to the three-necked flask, and the reaction is carried out at 30°C for 4 hours under nitrogen atmosphere. The synthesized gel block was sheared and crushed, then washed three times with ethanol, and finally vacuum dried to constant weight to obtain the target product, salt-resistant adamantyl amphiphilic polymer (P(AM / MAPS / N-ADA)), whose viscosity-average molecular weight was measured to be 14 million.

[0053] The ionic composition of the mineralized water is shown in Table 1.

[0054] Table 1. Ionic composition of mineralization

[0055]

[0056] The preparation method of the above-mentioned enhanced supramolecular inclusion polymer oil displacement system includes the following steps:

[0057] Prepare mineralized water with a mineralization degree of 32868 mg / L (ionic composition as shown in Table 1), stir for 15 minutes to ensure that the inorganic salts are fully dissolved and mixed evenly; add erucic acid amyl betaine amphoteric surfactant to the mineralized water, stir for 20 minutes to ensure that it is completely dissolved; add the host β-cyclodextrin polymer and the guest salt-resistant adamantyl amphiphilic polymer to the prepared surfactant solution, stir at room temperature for 2 hours to ensure that the polymer is fully dispersed and evenly dispersed, and then let it stand and mature in a constant temperature oven at 50℃ for 24 hours to obtain an enhanced supramolecular inclusion polymer oil displacement system.

[0058] Viscosity test: At a high temperature of 85℃ and a viscometer speed of 6 rpm, the viscosity of the oil displacement system was measured to be up to 98 mPa·s.

[0059] The system was sheared for 10 minutes at a rotation speed of 200 rpm / min, and then the viscosity retention rate of the oil displacement system was tested at 85℃ and a viscometer rotation speed of 6 rpm, and it was found to be 95.6%.

[0060] Oil-water interfacial tension test: Oil droplets are injected into a liquid glass capillary and suspended in the oil displacement system, and then subjected to high-speed rotation (6000 r·min). -1 The oil droplets were stretched and deformed, and their equilibrium interfacial tension at 85°C was measured. The oil displacement system of this invention can reduce the oil-water interfacial tension to 0.0019 mN·m. -1 This achieves an ultra-low interfacial tension level. The effect of reducing interfacial tension is as follows: Figure 3 .

[0061] Oil displacement test:

[0062] In an artificial simulated rock core (95 mm long, 25 mm in diameter, porosity 22.53%, permeability 537.8 × 10⁻⁶), -3 μm 2 In the displacement experiment, the crude oil viscosity was 70.8 mPa·s (85℃). Water flooding was first performed until the water cut reached 99%, followed by injection of a 0.5 PV oil displacement system, and finally, subsequent water flooding was carried out until no oil was found in the core. Under conditions of 27.6% bound water saturation, a 99% water cut, and 0.5 PV injection, the cumulative oil recovery rate was 81.6%. After the enhancement of the supramolecular inclusion polymer flooding system, the oil recovery rate increased significantly, with an improvement of up to 26.13%. The displacement effect was as follows: Figure 1 and Figure 2 As shown in the figure, after the oil displacement system with a capacity of 0.5 PV, the water cut decreased significantly and the oil recovery rate increased significantly, indicating that the oil displacement system has excellent performance in expanding the swept volume and improving the oil displacement efficiency under high temperature and high salinity conditions.

[0063] Example 2

[0064] An enhanced supramolecular inclusion polymer oil displacement system comprises the following raw material components by weight: 2g of β-cyclodextrin polymer, 1g of salt-resistant adamantyl amphiphilic polymer (P(AM / MAPS / N-ADA)), 1g of amphoteric surfactant erucamide propyl betaine, and 1000g of mineralized water with a mineralization degree of 32868mg / L.

[0065] The preparation methods of the β-cyclodextrin polymer and the salt-resistant adamantyl amphiphilic polymer, as well as the composition of the mineralized water, are the same as in Example 1.

[0066] The preparation method of the oil displacement system is the same as in Example 1.

[0067] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 80.7 mPa·s at a viscometer speed of 6 rpm.

[0068] The viscosity retention rate of the oil displacement system was tested at 85℃ and 6 rpm after shearing for 10 min at a rotation speed of 200 rpm. The results showed that the system retained 85.3% of the viscosity.

[0069] The oil-water interfacial tension test method is the same as in Example 1; the oil-water interfacial tension is 0.0025 mN·m. -1 .

[0070] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 70.31%, and the increase in crude oil recovery rate after the oil displacement system is only 20.61%.

[0071] Example 3

[0072] An enhanced supramolecular inclusion polymer oil displacement system comprises the following raw material components by weight: 2g of β-cyclodextrin polymer, 2g of salt-resistant adamantyl amphiphilic polymer (P(AM / MAPS / N-ADA)), 0.5g of amphoteric surfactant erucamide propyl betaine, and 1000g of mineralized water with a mineralization degree of 32868mg / L.

[0073] The preparation methods of the β-cyclodextrin polymer and the salt-resistant adamantyl amphiphilic polymer, as well as the composition of the mineralized water, are the same as in Example 1.

[0074] The preparation method of the oil displacement system is the same as in Example 1.

[0075] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 66.9 mPa·s at a viscometer speed of 6 rpm.

[0076] The viscosity retention rate of the oil displacement system was tested at 85℃ and 6 rpm after shearing for 10 min at a rotation speed of 200 rpm. The results showed that the system retained 86.9% of the viscosity.

[0077] The oil-water interfacial tension was tested using the same method as in Example 1; the oil-water interfacial tension was 0.0056 mN·m. -1 .

[0078] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 75.62%, and the increase in crude oil recovery rate after the oil displacement system is only 18.73%.

[0079] Example 4

[0080] An enhanced supramolecular inclusion polymer flooding system is described in Example 1, except that the amphoteric surfactant erucamide propyl betaine is replaced with erucamide propyl hydroxysulfonamide betaine; the composition of other raw materials and the preparation method of the raw materials are the same as in Example 1.

[0081] The preparation method of the oil displacement system is the same as in Example 1.

[0082] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 58.63 mPa·s at a viscometer speed of 6 rpm.

[0083] The viscosity retention rate of the oil displacement system was tested at 85℃ and 6 rpm after shearing for 10 min at a rotation speed of 200 rpm. The results showed that the system retained 72.3% viscosity.

[0084] The oil-water interfacial tension was tested using the same method as in Example 1; the oil-water interfacial tension was 0.0153 mN·m. -1 .

[0085] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 67.38%, and the increase in crude oil recovery rate after the oil displacement system is only 15.67%.

[0086] Example 5

[0087] An enhanced supramolecular inclusion polymer oil displacement system, as described in Example 1, except that: in the preparation of the β-cyclodextrin polymer, the molar amount of acrylamide is 0.8975 mol, the molar amount of 2-acrylamide-2-methylpropanesulfonic acid (AMPS) is 0.1 mol, and the molar amount of allyl-β-cyclodextrin (A-β-CD) is 0.025 mol; the composition of other raw materials and the preparation method of raw materials are the same as in Example 1.

[0088] The preparation method of the oil displacement system is the same as in Example 1.

[0089] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 84.2 mPa·s at a viscometer speed of 6 rpm.

[0090] The system was sheared for 10 minutes at a rotation speed of 200 rpm / min, and then the viscosity retention rate of the oil displacement system was tested at 85℃ and a viscometer rotation speed of 6 rpm, which was 86.5%.

[0091] The oil-water interfacial tension was tested using the same method as in Example 1; the oil-water interfacial tension was 0.0035 mN·m. -1 .

[0092] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 77.22%, and the increase in crude oil recovery rate after the oil displacement system is only 17.65%.

[0093] Example 6

[0094] An enhanced supramolecular inclusion polymer flooding system is described in Example 1, except that in the preparation of the salt-resistant adamantane amphiphilic polymer (P(AM / MAPS / N-ADA)), the molar amount of acrylamide is 0.9775 mol, the molar amount of salt-resistant monomer MAPS is 0.02 mol, and the molar amount of acrylamide-adamantane monomer is 0.025 mol; the composition of other raw materials and the raw material preparation method are the same as in Example 1.

[0095] The preparation method of the oil displacement system is the same as in Example 1.

[0096] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 89.3 mPa·s at a viscometer speed of 6 rpm.

[0097] The system was sheared for 10 minutes at a rotation speed of 200 rpm / min, and then the viscosity retention rate of the oil displacement system was tested at 85℃ and a viscometer rotation speed of 6 rpm, and it was found to be 90.2%.

[0098] The oil-water interfacial tension was tested using the same method as in Example 1; the oil-water interfacial tension was 0.0042 mN·m. -1 .

[0099] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 73.54%, and the increase in crude oil recovery rate after the oil displacement system is only 18.98%.

[0100] Comparative Example 1

[0101] An oil displacement system, as described in Example 1, except that no amphoteric surfactant is added; specifically, it comprises the following raw material composition by weight: 2g of β-cyclodextrin polymer, 2g of salt-resistant adamantyl amphiphilic polymer (P(AM / MAPS / N-ADA)), and 1000g of mineralized water with a mineralization degree of 32868mg / L.

[0102] The preparation methods of the β-cyclodextrin polymer and the salt-resistant adamantyl amphiphilic polymer, as well as the composition of the mineralized water, are the same as in Example 1.

[0103] The preparation method of the oil displacement system is the same as in Example 1, except that no amphoteric surfactant is added.

[0104] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 40 mPa·s at a viscometer speed of 6 rpm.

[0105] The viscosity retention rate of the oil displacement system was tested at 85℃ and 6 rpm after shearing for 10 min at a rotation speed of 200 rpm. The results showed that the system retained 72.84% of the viscosity.

[0106] The oil-water interfacial tension was tested using the same method as in Example 1; the oil-water interfacial tension was 2.3 mN·m. -1 .

[0107] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 63.2%, and the increase in crude oil recovery rate after the oil displacement system is only 10.3%.

[0108] Therefore, the enhanced supramolecular inclusion polymer flooding system of Example 1 of the present invention has superior viscosity-enhancing properties, reduces interfacial tension, and improves crude oil recovery.

[0109] Comparative Example 2

[0110] An oil displacement system comprises the following raw material components by weight: 2g of β-cyclodextrin polymer, 2g of single-tailed hydrophobic long-chain amphiphilic polymer (AP-C16 amphiphilic polymer with a carbon chain length of 16), 1g of amphoteric surfactant erucamide propyl betaine, and 1000g of mineralized water with a mineralization degree of 32868mg / L.

[0111] The preparation method of the β-cyclodextrin polymer and the composition of the mineralized water are the same as in Example 1.

[0112] The preparation method of the above-mentioned oil displacement system is the same as that in Example 1, except that the salt-resistant adamantyl amphiphilic polymer is replaced with a single-tailed hydrophobic long-chain amphiphilic polymer (AP-C16 amphiphilic polymer with a carbon chain length of 16).

[0113] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 38 mPa·s at a viscometer speed of 6 rpm.

[0114] The oil displacement system was sheared for 10 minutes at a rotation speed of 200 rpm / min, and then the viscosity retention rate was tested at 85℃ and a viscometer rotation speed of 6 rpm, which showed that the viscosity retention rate was 75.5%.

[0115] The oil-water interfacial tension testing method is the same as in Example 1; this oil displacement system can reduce the oil-water interfacial tension to 0.0145 mN·m. -1 It did not reach the level of ultra-low interfacial tension.

[0116] The oil displacement test method was the same as in Example 1; the cumulative crude oil recovery rate was 63.6%, and the crude oil recovery rate increased by 17.33% after the oil displacement system was applied, which is quite different from Example 1.

[0117] Comparative Example 3

[0118] An oil displacement system, as described in Comparative Example 2, except that no amphoteric surfactant is added; specifically, it comprises the following raw material composition by weight: 2g of β-cyclodextrin polymer, 2g of single-tailed hydrophobic long-chain amphiphilic polymer (AP-C16 amphiphilic polymer with a carbon chain length of 16), and 1000g of mineralized water with a mineralization degree of 32868mg / L.

[0119] The preparation method of β-cyclodextrin polymer and the composition of mineralized water are the same as those in Comparative Example 2.

[0120] The preparation method of the oil displacement system is the same as that of Comparative Example 2, except that no amphoteric surfactant is added.

[0121] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 28 mPa·s at a viscometer speed of 6 rpm.

[0122] The viscosity retention rate of the oil displacement system was tested at 200 rpm / min for 10 min, and then at 85℃ and a viscometer speed of 6 rpm. The result was 67.6%.

[0123] The oil-water interfacial tension was tested using the same method as in Example 1; the oil-water interfacial tension was 3.1 mN·m. -1 .

[0124] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 59.6%, and the increase in crude oil recovery rate after the oil displacement system is only 9.6%.

[0125] Comparative Example 4

[0126] An enhanced supramolecular inclusion polymer oil displacement system is described in Example 1, except that 2-acrylamide-2-methylpropanesulfonic acid (AMPS) is replaced with acrylic acid in the preparation of the β-cyclodextrin polymer; the other raw material composition and preparation method are the same as in Example 1.

[0127] The preparation method of the oil displacement system is the same as in Example 1.

[0128] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 55.6 mPa·s at a viscometer speed of 6 rpm.

[0129] The viscosity retention rate of the oil displacement system was tested at 85℃ and 6 rpm after shearing for 10 min at a rotation speed of 200 rpm. The results showed that the system retained 79.1% of the viscosity.

[0130] The oil-water interfacial tension was tested using the same method as in Example 1; the oil-water interfacial tension was 0.084 mN·m. -1 .

[0131] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 65.32%, and the increase in crude oil recovery rate after the oil displacement system is only 13.50%.

[0132] Comparative Example 5

[0133] An enhanced supramolecular inclusion polymer flooding system is described in Example 1, except that the salt-resistant monomer MAPS is replaced with acrylic acid in the preparation of the salt-resistant adamantyl amphiphilic polymer (P(AM / MAPS / N-ADA)); the other raw material composition and preparation methods are the same as in Example 1.

[0134] The preparation method of the oil displacement system is the same as in Example 1.

[0135] Viscosity test: At a high temperature of 85℃, the viscosity of the oil displacement system was measured to be 36.3 mPa·s at a viscometer speed of 6 rpm.

[0136] The viscosity retention rate of the oil displacement system was tested at 85℃ and 6 rpm after shearing for 10 min at a rotation speed of 200 rpm. The results showed that the system retained 74.5% of the viscosity.

[0137] The oil-water interfacial tension was tested using the same method as in Example 1; the oil-water interfacial tension was 0.025 mN·m. -1 .

[0138] The oil displacement test method is the same as in Example 1; the cumulative crude oil recovery rate is only 62.68%, and the increase in crude oil recovery rate after the oil displacement system is only 12.57%.

[0139] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of them. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention. Although the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A synergistic supramolecular inclusion polymer flooding system, characterized in that, The product comprises the following raw materials: a host polymer, a guest amphiphilic polymer, an amphoteric surfactant, and mineralized water; the host polymer is a β-cyclodextrin polymer; the guest amphiphilic polymer is a salt-resistant adamantyl alkyl amphiphilic polymer; and the amphoteric surfactant is selected from betaine-type amphoteric surfactants. The preparation method of β-cyclodextrin polymer includes the following steps: dissolving acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and allyl-β-cyclodextrin in distilled water, adding NaOH to adjust the pH of the system to neutral, then adding the initiator azobisisobutyramidine hydrochloride, reacting, and then pulverizing, washing and drying to obtain β-cyclodextrin polymer; the molar ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and allyl-β-cyclodextrin is 30-36:4-10:1; The preparation method of the salt-resistant adamantyl amphiphilic polymer includes the following steps: dissolving acrylamide, salt-resistant monomer MAPS, and acrylamide-adamantane in distilled water, adding ammonium persulfate and sodium bisulfite, reacting, and then pulverizing, washing, and drying to obtain the salt-resistant adamantyl amphiphilic polymer; the molar ratio of acrylamide, salt-resistant monomer MAPS, and acrylamide-adamantane is 35-40:0.8-2:1; the salt-resistant monomer MAPS is sodium 3-(N-allyl-N-methylamino)propane-1-sulfonate; The amphoteric surfactant is erucamide propyl betaine or erucamide propyl hydroxysulfonamide betaine.

2. The enhanced supramolecular inclusion polymer flooding system according to claim 1, characterized in that, The preparation method of β-cyclodextrin polymer includes one or more of the following conditions: The molar ratio of i. acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and allyl-β-cyclodextrin is 31.9:8:1; ii. The total mass ratio of acrylamide, 2-acrylamide-2-methylpropanesulfonic acid and allyl-β-cyclodextrin monomers to distilled water is 0.1-0.5:1; iii. The mass of the initiator azobisisobutyramidine hydrochloride is 0.02%-0.05% of the total mass of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and allyl-β-cyclodextrin monomers; iv. The reaction temperature is 38-45℃, the reaction time is 2-6h, and the reaction is carried out under nitrogen or argon protection.

3. The enhanced supramolecular inclusion polymer flooding system according to claim 1, characterized in that, The preparation method of salt-resistant adamantyl amphiphilic polymers includes one or more of the following conditions: i. The molar ratio of acrylamide, salt-resistant monomer MAPS, and acrylamide-adamantane is 38.7: 1.2:1; ii. The mass ratio of acrylamide, salt-tolerant monomer MAPS, acrylamide-adamantane monomer, and distilled water is 0.1-0.5:1; iii. The mass ratio of ammonium persulfate to sodium bisulfite is 2-4:1; the total mass of ammonium persulfate and sodium bisulfite is 0.1-0.3% of the total mass of acrylamide, salt-tolerant monomer MAPS, and acrylamide-adamantane monomer. iv. The reaction temperature is 25-35℃, the reaction time is 2-6h, and the reaction is carried out under nitrogen or argon protection.

4. The enhanced supramolecular inclusion polymer flooding system according to claim 1, characterized in that, Includes one or more of the following conditions: i. The viscosity-average molecular weight of the host polymer and the guest amphiphilic polymer is 4 × 10⁻⁶. 6 ~2×10 7 ; ii. The mineralization degree of the mineralized water is 1000 mg / L to 100000 mg / L.

5. The enhanced supramolecular inclusion polymer flooding system according to claim 1, characterized in that, The mass ratio of the host polymer, the guest amphiphilic polymer, the amphoteric surfactant, and the mineralized water is 1-5:1-5:0.5-2:800-1200.

6. The preparation method of the enhanced supramolecular inclusion polymer oil displacement system according to any one of claims 1-5, comprising the steps of: dissolving an amphoteric surfactant in mineralized water; adding a host polymer and a guest amphiphilic polymer and dispersing them fully; and then allowing them to stand and mature to obtain the enhanced supramolecular inclusion polymer oil displacement system.

7. The preparation method of the enhanced supramolecular inclusion polymer oil displacement system according to claim 6, characterized in that, Includes one or more of the following conditions: i. Add the amphoteric surfactant to the mineralized water and stir at room temperature for 10-30 minutes to ensure that the amphoteric surfactant is fully dissolved in the mineralized water; ii. To ensure thorough dispersion, stir at room temperature for 1-3 hours; iii. The static curing temperature is 40-60℃, and the static curing time is 20-30 hours.

8. The application of the enhanced supramolecular inclusion polymer flooding system as described in any one of claims 1-5, applied to tertiary oil recovery in oil fields to improve crude oil recovery rate.

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