Composition with oil displacement function, application of composition and thickened oil recovery method

Abstract

The invention relates to the technical field of oilfield development, and discloses a composition with an oil displacement function, application of the composition and a thickened oil recovery method. The composition comprises a nano material, a surfactant and a polymer, wherein the surfactant is selected from at least one of fatty alcohol polyether sulfonate, fatty alcohol polyether sulfate, a gemini surfactant containing a sulfonic acid group, a glycoside compound, an alcohol amine compound and an amide compound containing a hydroxyl group; wherein the mass ratio of the nano material to the surfactant is (0.1-2): 1. The aqueous solution of the composition has the characteristics of high viscosity and low interfacial tension in indoor experiments and field application, and can reduce the average water content of high-calcium-magnesium oil reservoirs and improve the crude oil recovery rate, thereby greatly improving the oil quantity and benefits of low-yield and low-efficiency wells.

Description

Technical Field

[0001] This invention relates to the field of oilfield development technology, specifically to a composition with oil displacement function and its application and method for heavy oil extraction. Background Technology

[0002] Polymer flooding is the most important technology in chemical flooding. By adding water-soluble polymers to the injection water, the viscosity of the displaced phase is increased, the oil-water mobility ratio is adjusted, the swept volume of the displaced phase is expanded, and the oil washing efficiency is enhanced, thus significantly improving the oil displacement efficiency. Polymer flooding is simple to operate, has low cost, and can be used in combination with profile control and water shut-off agents, also having a certain permeability adjustment effect. As a synthetic water-soluble polymer, polyacrylamide and its derivatives are currently the most widely used and effective polymer flooding agents in chemical flooding. According to the structure of polyacrylamide, it can be divided into linear polyacrylamide and cross-linked polyacrylamide. Partially hydrolyzed linear polyacrylamide (HPAM) is used as an oil displacement agent mainly because it increases the viscosity of the aqueous solution, thereby increasing the swept volume and improving the mobility ratio. However, the poor temperature and salt resistance of linear polyacrylamide solutions is a technical bottleneck for its application in high-temperature reservoirs and reservoirs after polymer flooding, which seriously affects its actual performance.

[0003] Cross-linked polyacrylamide is mostly cross-linked in situ underground. Cross-linking agents are generally organochromium, organoaluminum, organozirconium, water-soluble phenolic resins, etc., and are formed by cross-linking linear HPAM underground with the cross-linking agent. Cross-linked polyacrylamide can be used as a profile control and water shut-off agent and an oil displacement agent because its good swelling properties allow for profile control and permeability adjustment in high-permeability layers. However, fully cross-linked polyacrylamide, due to its high degree of cross-linking, high hardness, and poor deformability, has difficulty migrating in pores and is therefore limited in its use as an oil displacement agent. When used as an oil displacement agent, the polymer suspension must have good transport ability, be able to deform and pass through pores, and possess excellent viscoelastic properties to effectively increase the viscosity of the displaced phase and improve its mobility ratio. CN1105417A discloses a crosslinked polymer flooding agent and its preparation method. It utilizes chromium lactate as a crosslinking agent to transform polymers into crosslinked polymers, thereby solving the problems of poor salt resistance and susceptibility to mechanical shearing. In this patent, the concentration of the polyacrylamide aqueous solution is preferably 800-8000 mg / L, and the preferred dosage of chromium lactate is 300-3000 mg / L. The disadvantages of this technical solution are: because the small-molecule crosslinking agent leads to a large number of intramolecular crosslinking reactions in the polymer, the amount of crosslinking agent used is relatively large, and chromium ions, as a heavy metal, cause significant pollution, which is detrimental to safety and environmental protection. CN1197101A discloses the use of aluminum citrate as a crosslinking agent to replace part of the polyacrylamide in polymer flooding technology. While ensuring that the injection viscosity does not decrease and is appropriately increased, the amount of polyacrylamide used is reduced, thereby reducing injection costs. However, the increase in injection viscosity is only 0-25%. CN105154054B provides a cross-linked polymer oil displacement agent synthesized with the participation of a triamine. It uses pentamethyldiethylenetriamine (PMTDA) as a functional monomer and cross-linking agent, and potassium sulfate-sodium bisulfite as an initiating system to prepare a partially cross-linked polymer oil displacement agent containing a large number of branched structures. However, the system has low salt tolerance, and in particular, high concentrations of calcium and magnesium ions significantly reduce the viscosity of the system.

[0004] To overcome the above-mentioned deficiencies, there is a need for a composition with oil displacement function and its application in heavy oil extraction methods. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of poor temperature resistance, calcium and magnesium ion resistance, and ferrous ion resistance in the existing technology, and to provide a composition with oil displacement function and its application in heavy oil extraction methods.

[0006] To achieve the above objectives, a first aspect of the present invention provides a composition having an oil-removing function, characterized in that the composition comprises nanomaterials, surfactants, and polymers;

[0007] The surfactant is selected from at least one of fatty alcohol polyether sulfonates, fatty alcohol polyether sulfates, sulfonic acid-containing gemini surfactants, alkanolamine compounds, and hydroxyl-containing amide compounds; the polymer includes structural units provided by acrylamide.

[0008] The mass ratio of the nanomaterial to the surfactant is 0.1-2:1.

[0009] The second aspect of this invention provides the application of the composition described in the first aspect of this invention as an oil displacement agent, particularly its application as an oil displacement agent in enhancing the oil recovery rate of an oil reservoir, wherein the total calcium and magnesium ion content in the oil reservoir is ≥1000 mg / L, the ferrous ion content is ≤10 mg / L, the temperature of the oil reservoir is ≥50°C, the viscosity at 60°C is 60-150 mPa·s, and the salinity of the oil reservoir is ≥2×10⁻⁶. 4 mg / L.

[0010] A third aspect of the present invention provides a method for heavy oil extraction, characterized in that the method comprises: mixing an aqueous solution of a composition with heavy oil to obtain a mixture containing heavy oil;

[0011] The composition is selected from the compositions described in the first aspect of the present invention.

[0012] Through the above technical solution, under the conditions of reservoir temperature of 62℃, shear rate of 6rpm, mineralization of 25000mg / L and total calcium and magnesium ion concentration of 1200mg / L, the viscosity of a 1500mg / L solution of the composition described in this invention can reach 76-80mPa·s in indoor experiments and field applications, which is 5 times higher than the viscosity of a pure polymer system of the same concentration.

[0013] The interfacial tension, measured using a rotating drop interfacial tensiometer at 62℃ and 5000 rpm, reached 5.0-5.8 × 10⁻⁶ during both indoor experiments and field applications. -4 mN / m.

[0014] In indoor core displacement experiments, the experimental temperature was 62℃, and the mineralization was 25000 mg / L NaCl and 1200 mg / L Ca. 2+ Under these conditions, a solution of the composition described in this invention can increase oil recovery by at least about 28%.

[0015] After injecting the solution of the composition described in this invention into the reservoir one year later, the water injection pressure increased by 3-5 MPa, the average water cut of 10 oil wells decreased from 98% to 95%, and the daily oil production of the oil wells increased from 0.5 tons to 2 tons, which greatly improved the oil production and efficiency of low-yield and inefficient wells and improved the recovery rate of crude oil in high-calcium and magnesium reservoirs. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] As previously stated, the first aspect of the present invention provides a composition having an oil displacement function, characterized in that the composition comprises nanomaterials, surfactants, and polymers;

[0018] The surfactant is selected from at least one of fatty alcohol polyether sulfonates, fatty alcohol polyether sulfates, sulfonic acid-containing gemini surfactants, glycosides, alkanolamines, and hydroxyl-containing amides; the polymer includes structural units provided by acrylamide.

[0019] The mass ratio of the nanomaterial to the surfactant is 0.1-2:1.

[0020] In some embodiments of the present invention, preferably, the nanomaterial is selected from at least one of oxide nanomaterials, carbonate nanomaterials and silicate nanomaterials, more preferably from oxide nanomaterials and / or carbonate nanomaterials.

[0021] In some embodiments of the present invention, preferably, the oxide nanomaterial is selected from at least one of modified silica nanomaterials, modified graphene oxide nanomaterials, and modified zirconium oxide nanomaterials.

[0022] In some embodiments of the present invention, preferably, the carbonate nanomaterial is selected from at least one of calcium carbonate nanomaterial, magnesium carbonate, and barium carbonate.

[0023] In some embodiments of the present invention, preferably, the fatty alcohol polyether sulfonate is selected from at least one of sodium butanol polyether sulfonate, sodium hexanol polyether sulfonate, and sodium octyl alcohol polyether sulfonate, and more preferably sodium butanol polyether sulfonate.

[0024] In some embodiments of the present invention, preferably, the fatty alcohol polyether sulfate is selected from at least one of sodium butanol polyether sulfate, sodium hexanol polyether sulfate, and sodium octyl alcohol polyether sulfate, and more preferably sodium butanol polyether sulfate.

[0025] In some embodiments of the present invention, preferably, the sulfonic acid-containing gemini surfactant is selected from at least one of sodium dodecyl sulfonate, sodium hexadecyl sulfonate, and sodium octadecyl sulfonate, and more preferably from sodium dodecyl sulfonate.

[0026] In some embodiments of the present invention, preferably, the hydroxyl-containing amide compound is selected from at least one of hydroxypropionamide, N-hydroxysuccinimide and N-hydroxyacrylamide, and more preferably from hydroxypropionamide.

[0027] In some embodiments of the present invention, preferably, the mass ratio of the nanomaterial to the surfactant is 1.2-1.8:1, more preferably 0.5-1.5:1.

[0028] In some embodiments of the present invention, preferably, the mass ratio of the polymer to the surfactant is 100-1000:1.

[0029] In some embodiments of the present invention, preferably, the polymer is selected from at least one of polyacrylamide, diacrylamide, and multi-component copolyacrylamide; more preferably, it is selected from multi-component copolyacrylamide.

[0030] In this invention, the nanomaterial modification refers to surface modification of the nanomaterial to increase its salt resistance and dispersion stability. For example, the nanomaterial can be modified with sodium dodecyl sulfate (SDS), thus becoming an SDS-modified nanomaterial. The binary polyacrylamide refers to a binary polyacrylamide formed from 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and acrylamide. The multi-component polyacrylamide is a multi-component polymer formed from AMPS, hexadecene sulfonate, and acrylamide.

[0031] In some embodiments of the present invention, preferably, the weight-average molecular weight of the polymer is 8,000,000-1,500,000 g / mol.

[0032] In some embodiments of the present invention, preferably, the degree of hydrolysis of the polymer is 18-20%.

[0033] The second aspect of this invention provides the application of the composition described in the first aspect of this invention as an oil displacement agent, particularly its application as an oil displacement agent in enhancing the oil recovery rate of an oil reservoir, wherein the total calcium and magnesium ion content in the oil reservoir is ≥1000 mg / L, the ferrous ion content is ≤10 mg / L, the temperature of the oil reservoir is ≥50°C, the viscosity at 60°C is 60-150 mPa·s, and the salinity of the oil reservoir is ≥2×10⁻⁶. 4 mg / L.

[0034] A third aspect of the present invention provides a method for heavy oil extraction, characterized in that the method comprises: mixing an aqueous solution of a composition with heavy oil to obtain a mixture containing heavy oil;

[0035] The composition is selected from the compositions described in the first aspect of the present invention.

[0036] According to a particularly preferred embodiment of the present invention, the composition comprises a ternary polymer, nano-calcium carbonate and sodium didodecyl sulfonate, wherein the mass ratio of nano-calcium carbonate to sodium didodecyl sulfonate is 1.8-2:1, and the mass ratio of polymer to surfactant is 750-850:1.

[0037] The present invention will be described in detail below through examples. In the following examples, the nanomaterials are commercially available products from Ningbo Fengcheng Nanotechnology Co., Ltd.; the surfactants are commercially available products from Beijing Chemical Reagent Co., Ltd.

[0038] Example 1

[0039] This example illustrates indoor experimental methods.

[0040] First, a 10,000 mg / L stock solution of SNF's multi-component copolymer (AMPS, sodium hexadecene sulfonate, and acrylamide copolymerized into a ternary polymer with a weight-average molecular weight of 12,000,000 g / mol, a degree of hydrolysis of 18%, and brand name: SuperPusher 8525) was prepared using simulated saline with a total mineralization of 25,000 mg / L, a calcium ion concentration of 1200 mg / L, and a ferrous ion concentration of 10 mg / L. Simultaneously, a 1% by weight simulated saline solution of nano-synergist (modified graphene oxide nanomaterials and sodium butanol polyether sulfonate in a 1:1 mass ratio) was prepared. After the polymer stock solution was allowed to stand for 12 hours, a certain amount of the polymer stock solution was weighed, and then the nano-synergist solution was added to dilute the polymer stock solution, so that the mass ratio of the polymer to the surfactant in the final chemical binary displacement system was 1000:1. After magnetic stirring for 5 minutes, samples were taken to test the viscosity, interfacial tension, and oil displacement performance of the chemical binary displacement system. The viscosity of the binary oil displacement system was determined using a Brookfield rotational viscometer. At 62°C and a shear rate of 6 r / min, the viscosity of a 1500 mg / L multi-component copolymer solution was 16 mPa·s. After treatment with 1% by weight of nano-synergist, the viscosity of the chemical binary oil displacement composite system increased to 80 mPa·s, a five-fold increase compared to the initial polymer viscosity. The interfacial tension was measured to be 5.0 × 10⁻⁶ mPa·s using a rotating drop interfacial tensiometer at 62°C and 5000 rpm. -4 mN / m.

[0041] The core used for the core displacement experiment was Bailey sandstone, 30 cm long, 2.5 cm in inner diameter, with a permeability of 1200 mD and a pore volume of 38 mL. The entire displacement experiment was conducted in a digitally controlled temperature chamber, with a fluid injection rate of 0.3 mL / min, an experimental temperature of 62℃, and a salinity of 25000 mg / L NaCl and 1200 mg / L Ca. 2+ Laboratory core flooding followed by waterflooding using a chemical binary system increased oil recovery by approximately 28%.

[0042] Example 2

[0043] This example illustrates the application methods in mining operations.

[0044] Wastewater from oilfield treatment (total mineralization around 25,000 mg / L, calcium and magnesium ion concentration around 1,200 mg / L, ferrous ion concentration around 10 mg / L) was used to prepare a 10,000 mg / L mother liquor of SNF's multi-component copolymer (AMPS, sodium hexadecene sulfonate, and acrylamide copolymerized into a ternary polymer, weight average molecular weight 12,000,000 g / mol, degree of hydrolysis 18%, brand name: SuperPUSHER 8525) in a closed rapid dissolving device (PSU complete set of equipment from Aisen Flocculant Company). At the same time, a nano-synergist (modified graphene oxide nanomaterials and sodium butanol polyether sulfonate in a mass ratio of 1:1) was added to the high-pressure injection water pipeline at a concentration of 1%. Then, a certain amount of mother liquor was pumped in by a plunger pump, so that the mass ratio of the polymer to the surfactant was 1000:1. After being mixed evenly in a static mixer, it was injected into each water well through the pipeline. The viscosity of the injected system was monitored by sampling at the wellhead using a closed-loop pressure sampling method. The viscosity of the chemical binary system was monitored using a rotational viscometer. Under reservoir conditions of 62℃ and a shear rate of 6 r / min, the viscosity of the 1500 mg / L chemical binary solution was 76 mPa·s, approximately 5 times higher than that of the 1500 mg / L pure polymer system. The interfacial tension was measured to be 5.0 × 10⁻⁶ mPa·s using a rotating drop interfacial tensiometer at 62℃ and 5000 rpm. -4 mN / m.

[0045] One year after the injection, the results showed that the water injection pressure increased by 3-5 MPa, the average water cut of the 10 oil wells decreased from 98% to 95%, and the average daily oil production per well increased from 0.5 tons to 2.5 tons, with a cumulative increase of 3,000 tons of oil.

[0046] Example 3

[0047] First, a 6000 mg / L stock solution of SNF's multi-component copolymer (AMPS, sodium hexadecene sulfonate, and acrylamide copolymerized into a ternary polymer with a weight-average molecular weight of 10,000,000 g / mol, a degree of hydrolysis of 20%, and brand name: SuperPusher 8525) was prepared using simulated saline with a total mineralization of 30,000 mg / L, a calcium ion concentration of 1,500 mg / L, and a ferrous ion concentration of 8 mg / L. Simultaneously, a 1.5% simulated saline solution of nano-synergist (nano-calcium carbonate and sodium dodecyl sulfonate in a mass ratio of 2:1) was prepared. After the polymer stock solution was allowed to stand for 10 hours, a certain amount of the polymer stock solution was weighed, and then another certain amount was weighed. The nano-synergist solution was then added to dilute the polymer stock solution, ensuring that the mass ratio of the polymer to the surfactant in the final chemical binary displacement system was 800:1. After magnetic stirring for 5 minutes, samples were taken to test the viscosity, interfacial tension, and oil displacement performance of the chemical binary displacement system. The viscosity of the binary oil displacement system was determined using a Brookfield rotational viscometer. At 62°C and a shear rate of 6 r / min, the viscosity of a 2000 mg / L multi-component copolymer solution was 22 mPa·s. After treatment with 1.0% nano-synergist, the viscosity of the chemical binary oil displacement composite system increased to 100 mPa·s, approximately five times the initial polymer viscosity. The interfacial tension was measured to be 8.1 × 10⁻⁶ mPa·s using a rotating drop interfacial tensiometer at 70°C and 5000 rpm. -4 mN / m.

[0048] The core used for the core displacement experiment was Bailey sandstone, 30 cm long, 2.5 cm in inner diameter, with a permeability of 1200 mD and a pore volume of 38 mL. The entire displacement experiment was conducted in a digitally controlled temperature chamber, with a fluid injection rate of 0.2 mL / min, an experimental temperature of 70℃, and a salinity of 30000 mg / L NaCl and 1500 mg / L Ca. 2+ Laboratory core flooding followed by waterflooding using a chemical binary system increased oil recovery by approximately 31%.

[0049] Example 4

[0050] Wastewater from oilfield treatment (total mineralization around 25,000 mg / L, calcium and magnesium ion concentration around 1,200 mg / L, ferrous ion concentration around 10 mg / L) was used to prepare a 10,000 mg / L mother liquor of SNF's multi-component copolymer (AMPS, sodium hexadecene sulfonate, and acrylamide copolymerized into a ternary polymer, weight average molecular weight 10,000,000 g / mol, degree of hydrolysis 19%, brand name: SuperPUSHER 8525) in a closed rapid dissolving device (Aisen flocculant company's PSU complete set of equipment). At the same time, a nano-synergist (modified silica nanomaterials and sodium dodecyl sulfonate in a mass ratio of 1.2:1) was added to the high-pressure injection water pipeline at a concentration of 1.1%. Then, a certain amount of mother liquor was pumped in by a plunger pump, so that the mass ratio of the polymer and surfactant in the final polymer thickening system was 200:1. After being mixed evenly in a static mixer, it was injected into each water well through the pipeline. The viscosity of the injected system was monitored by sampling at the wellhead using a closed-loop pressure sampling method. The viscosity of the binary chemical system was monitored using a rotational viscometer. Under reservoir conditions of 62℃ and a shear rate of 6 r / min, the viscosity of a 2000 mg / L binary chemical solution was 96 mPa·s. The interfacial tension was measured to be 5.9 × 10⁻⁶ mPa·s using a rotating drop interfacial tensiometer at 62℃ and 5000 rpm. -4 mN / m.

[0051] Example 5

[0052] Wastewater from oilfield treatment (total mineralization around 25,000 mg / L, calcium and magnesium ion concentration around 1,200 mg / L, ferrous ion concentration around 5 mg / L) was used to prepare a 10,000 mg / L mother liquor of SNF's multi-component copolymer (AMPS, sodium hexadecene sulfonate, and acrylamide copolymerized into a ternary polymer, weight average molecular weight 8,000,000 g / mol, degree of hydrolysis 19%, brand name: SuperPusher 8525) in a closed rapid dissolving device (PSU complete set of equipment from Aisen Flocculant Company). At the same time, a nano-synergist (graphene oxide nanomaterials and sodium dodecyl sulfonate in a mass ratio of 2:1) was added to the high-pressure injection water pipeline at a concentration of 1.1%. Then, a certain amount of mother liquor was pumped in by a plunger pump, so that the mass ratio of the polymer and surfactant in the final polymer thickening system was 1,000:1. After being mixed evenly in a static mixer, it was injected into each water well through the pipeline. One year after the injection, the results showed that the injection pressure of well 1 increased from 6.6 MPa before injection to 9.0 MPa, an increase of 2.4 MPa; the injection pressure of well 2 increased from 4.6 MPa before injection to 7.6 MPa, an increase of 3 MPa; and the injection pressure of well 3 increased from 6 MPa before injection to 9 MPa, an increase of 3 MPa.

[0053] Example 6

[0054] Wastewater from oilfield treatment (total mineralization around 25,000 mg / L, calcium and magnesium ion concentration around 1,200 mg / L, ferrous ion concentration around 10 mg / L) was used to prepare a 10,000 mg / L mother liquor of SNF's multi-component copolymer (AMPS, sodium hexadecene sulfonate, and acrylamide copolymerized into a ternary polymer, weight average molecular weight 12,000,000 g / mol, degree of hydrolysis 20%, brand name: SuperPusher 8525) in a closed rapid dissolving device (PSU complete set of equipment from Aisen Flocculant Company). At the same time, a nano-synergist composition (nano-graphene oxide and sodium dodecyl sulfonate in a mass ratio of 2:1) was added to the high-pressure injection water pipeline at a concentration of 1.1%. Then, a certain amount of mother liquor was pumped in by a plunger pump, so that the mass ratio of the polymer and surfactant in the final polymer thickening system was 1000:1. After being mixed evenly in a static mixer, it was injected into each water well through the pipeline. One year after the injection, the results showed that the daily oil production of well 1 increased from 0.5 tons before polymer injection to 2.5 tons, an increase of 2 tons per day, and the water cut decreased from 98.3% to 94.2%; the daily oil production of well 2 increased from 1.0 tons before polymer injection to 2.0 tons, an increase of 1 ton per day, and the water cut decreased from 98% to 96%; and the daily oil production of well 5 increased from 0.6 tons before polymer injection to 1.5 tons, an increase of 0.9 tons per day, and the water cut decreased from 98.5% to 97%.

[0055] Example 7

[0056] The composition was prepared according to the method of Example 1, except that the nanomaterial was calcium carbonate, the viscosity of the chemical binary flooding composite system was 64 mPa·s, which was 4 times higher than the initial polymer viscosity; the interfacial tension was 5.0 × 10⁻⁶ mPa·s. -3 mN / m, the chemical binary system for oil recovery after waterflooding using laboratory core samples increased the oil recovery rate by approximately 18%.

[0057] Example 8

[0058] The composition was prepared according to the method of Example 1, except that the surfactant was sodium didodecyl sulfonate, the viscosity of the chemical binary displacement composite system was 65 mPa·s, which was 4 times higher than the initial polymer viscosity; and the interfacial tension was 1.0 × 10⁻⁶ mPa·s. -3 mN / m, the chemical binary system for oil recovery after water flooding in laboratory core samples increased crude oil recovery by approximately 20%.

[0059] Example 9

[0060] The composition was prepared according to the method of Example 1, except that the mass ratio of the nanomaterial to the surfactant was 2:1, the viscosity of the chemical binary flooding composite system was 130 mPa·s, which was 8 times higher than the initial polymer viscosity; and the interfacial tension was 5.0 × 10⁻⁶ mPa·s. -3 mN / m, the chemical binary system for oil recovery after waterflooding using laboratory core samples increased oil recovery by approximately 21%.

[0061] Example 10

[0062] The composition was prepared according to the method of Example 1, except that the mass ratio of the polymer to the surfactant was 200:1, the viscosity of the chemical binary displacement composite system was 160 mPa·s, which was 10 times higher than the initial polymer viscosity; and the interfacial tension was 5.0 × 10⁻⁶ mPa·s. -2 mN / m, the chemical binary system for oil recovery after water flooding in laboratory core samples increased the oil recovery rate by approximately 19%.

[0063] Example 11

[0064] The composition was prepared according to the method of Example 1, except that the surfactant was sodium hexanol polyether sulfonate, the viscosity of the chemical binary displacement composite system was 100 mPa·s, which was 6 times higher than the initial polymer viscosity; and the interfacial tension was 2.0 × 10⁻⁶ mPa·s. -3 mN / m, the chemical binary system for oil recovery after waterflooding using laboratory core samples increased crude oil recovery by approximately 15%.

[0065] Comparative Example 1

[0066] The composition was prepared according to the method of Example 1, except that the polymer was used to replace the nanomaterial in the nano-synergist. The viscosity of the chemical binary oil displacement composite system was 60 mPa·s, which was 4 times higher than the initial polymer viscosity; the interfacial tension was 5.0 × 10⁻⁶ mPa·s. -2 mN / m, the chemical binary system for oil recovery after water flooding in laboratory core samples increased the oil recovery rate by approximately 10%.

[0067] Comparative Example 2

[0068] The composition was prepared according to the method of Example 1, except that the polymer was used to replace the surfactant in the nano-synergist. The viscosity of the chemical binary oil displacement composite system was 70 mPa·s, which was 5 times higher than the initial polymer viscosity; the interfacial tension was 3.0 × 10⁻⁶ mPa·s. -3 mN / m, the chemical binary system for oil recovery after waterflooding using laboratory core samples increased crude oil recovery by approximately 15%.

[0069] Comparative Example 3

[0070] The composition was prepared according to the method of Example 1, except that the polymer was replaced with the nano-synergist in the composition. The viscosity of the chemical binary displacement composite system was 65 mPa·s, which was 4 times higher than the initial polymer viscosity; the interfacial tension was 8.0 × 10⁻⁶ mPa·s. -4 mN / m, the chemical binary system for oil recovery after water flooding in laboratory core samples increased the oil recovery rate by approximately 14%.

[0071] Comparative Example 4

[0072] The composition was prepared according to the method of Example 1, except that the mass ratio of the nanomaterial to the surfactant was 3:1, the viscosity of the chemical binary flooding composite system was 100 mPa·s, which was 6 times higher than the initial polymer viscosity; and the interfacial tension was 5.0 × 10⁻⁶ mPa·s. -2 mN / m, the chemical binary system for oil recovery after waterflooding using laboratory core samples increased oil recovery by approximately 16%.

[0073] The results of the above examples and comparative examples show that, compared with the comparative examples, the polymer aqueous solution using the technical solution of the present invention has the effects of high viscosity, low interfacial tension, high temperature resistance, high mineralization resistance, and resistance to magnesium ions in both indoor experiments and field applications. Furthermore, it has a significantly better effect in reducing the average water cut of high calcium-magnesium oil reservoirs and improving crude oil recovery.

[0074] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A composition having an oil displacement function, characterized in that, The composition includes nanomaterials, surfactants, and polymers; The surfactant is selected from at least one of fatty alcohol polyether sulfonates, fatty alcohol polyether sulfates, sulfonic acid-containing gemini surfactants, alkanolamine compounds, and hydroxyl-containing amide compounds; the polymer includes structural units provided by acrylamide. The mass ratio of the nanomaterial to the surfactant is 0.1-2:

1.

2. The composition according to claim 1, wherein, The nanomaterial is selected from at least one of oxide nanomaterials, carbonate nanomaterials and silicate nanomaterials, preferably selected from oxide nanomaterials and / or carbonate nanomaterials.

3. The composition according to claim 2, wherein, The oxide nanomaterial is selected from at least one of modified silica nanomaterials, modified graphene oxide nanomaterials, and modified zirconium oxide nanomaterials; And / or, the carbonate nanomaterial is selected from at least one of calcium carbonate nanomaterials, magnesium carbonate, and barium carbonate.

4. The composition according to any one of claims 1-3, wherein, The fatty alcohol polyether sulfonate is selected from at least one of sodium butanol polyether sulfonate, sodium hexanol polyether sulfonate and sodium octyl alcohol polyether sulfonate, preferably sodium butanol polyether sulfonate; And / or, the fatty alcohol polyether sulfate is selected from at least one of sodium butanol polyether sulfate, sodium hexanol polyether sulfate and sodium octyl alcohol polyether sulfate, preferably sodium butanol polyether sulfate; And / or, the sulfonic acid-containing gemini surfactant is selected from at least one of sodium dodecyl sulfonate, sodium hexadecyl sulfonate and sodium octadecyl sulfonate, preferably sodium dodecyl sulfonate; And / or, the hydroxyl-containing amide compound is selected from at least one of hydroxypropionamide, N-hydroxysuccinimide and N-hydroxyacrylamide, preferably selected from hydroxypropionamide.

5. The composition according to any one of claims 1-4, wherein, The mass ratio of the nanomaterial to the surfactant is 1.2-1.8:1, preferably 0.5-1.5:

1.

6. The composition according to any one of claims 1-4, wherein, The mass ratio of the polymer to the surfactant is 100-1000:

1.

7. The composition according to claim 1 or 6, wherein, The polymer is selected from at least one of polyacrylamide, binary polyacrylamide, and multi-component copolyacrylamide; preferably selected from multi-component copolyacrylamide.

8. The composition according to claim 1 or 6, wherein, The weight-average molecular weight of the polymer is 8,000,000-15,000,000 g / mol; Preferably, the degree of hydrolysis of the polymer is 18-20%.

9. The use of the composition according to any one of claims 1-8 as an oil displacement agent, particularly its use as an oil displacement agent in enhancing oil recovery from oil reservoirs, wherein, The reservoir has a total calcium and magnesium ion content ≥1000 mg / L, a ferrous ion content ≤10 mg / L, a reservoir temperature ≥50℃, a viscosity of 60-150 mPa·s at 60℃, and a salinity ≥2×10⁻⁶. 4 mg / L.

10. A method for heavy oil extraction, characterized in that, The method includes: mixing an aqueous solution of the composition with heavy oil to obtain a mixture containing heavy oil; The composition is selected from the compositions described in any one of claims 1-8.