Tertiary oil recovery method using composite oil-displacing agent and oil-displacing agent thereof

Abstract

The invention discloses a tertiary oil recovery method using a composite oil-displacing agent and the oil-displacing agent thereof, and belongs to the technical field of tertiary oil recovery. The composite oil displacement agent is prepared from the following components in percentage: 0.5 to 1.5 percent of quadripolymer, 0.1 to 0.3 percent of thickened oil penetrating agent, 0.3 to 1 percent of surfactant and the balance of water, the surface active agent comprises a lipopeptide biological surface active agent and sodium fatty alcohol-polyoxyethylene ether carboxylate; the quadripolymer is obtained by carrying out copolymerization on acrylamide, acryloyl morpholine, 2-acrylamide-2-methylpropanesulfonic acid and hexadecyl dimethyl allyl ammonium chloride; and the thick oil penetrating agent is octadecyl methacrylate or octadecyl acrylate. According to the present invention, the specific quadripolymer, the surfactant and the thick oil penetrating agent are compounded according to the specific ratio to obtain the composite oil displacement agent, such that the oil displacement efficiency can be improved, and the oil displacement agent has effects of salt resistance and high temperature resistance, and can meet the efficient tackifying requirement under the high temperature and high salinity condition.

Description

Technical Field

[0001] The present application relates to a tertiary oil recovery method using a composite oil displacement agent and the oil displacement agent thereof, belonging to the technical field of tertiary oil recovery. Background Art

[0002] Oil is an important energy source. Compared with coal, it has the advantages of high energy density, convenient transportation and storage, and less pollution to the atmosphere after combustion. Liquefied gas and pipeline gas made from oil are high-quality fuels for urban residents, and airplanes, tanks, ships, rockets and other spacecraft also use oil as fuel.

[0003] Oil production refers to the act of digging and extracting oil from where there are oil reserves. It is divided into three stages: primary oil recovery, which relies on the natural energy of the formation; secondary oil recovery, which is carried out through artificial water injection or gas injection; and tertiary oil recovery, which relies on physical and chemical methods. Among them, the main tertiary oil recovery methods are thermal drive, miscible drive, chemical drive and microbial drive.

[0004] Polymers can effectively increase the viscosity of water, thereby improving the oil-water mobility ratio, increasing the sweep coefficient of the oil displacement system, and thus increasing the crude oil recovery rate. Therefore, polymer flooding technology has become the main technical means for tertiary oil recovery. Most of the conventional polymers used in oil fields are partially hydrolyzed polyacrylamide, which has the following main problems: partially hydrolyzed polyacrylamide has a large relative molecular mass and a long carbon chain, and is easily degraded by shearing; at high mineralization, the partially hydrolyzed polyacrylamide molecular chain curls up, resulting in low viscosity of the polymer solution; at high temperatures, partially hydrolyzed polyacrylamide is easily hydrolyzed by temperature.

[0005] The existing partially hydrolyzed polyacrylamide as a polymer flooding agent has been unable to meet the requirements of high-efficiency viscosity increase under high temperature and high salinity conditions. With the continuous development of deep well high temperature and high salt reservoirs, it is of great practical significance to provide a high temperature and salt resistant high oil recovery efficiency flooding agent system. Summary of the invention

[0006] In order to solve the above problems, a tertiary oil recovery method using a composite oil-displacing agent and its oil-displacing agent are provided. The composite oil-displacing agent is obtained by compounding a specific tetrapolymer, a surfactant and a heavy oil penetrant in a specific ratio, which can improve the oil recovery efficiency. The oil-displacing agent is salt-resistant and high-temperature-resistant, and can meet the requirements of efficient viscosity increase under high-temperature and high-mineralization conditions.

[0007] According to one aspect of the present application, a composite oil displacement agent is provided, comprising the following percentages of components: 0.5-1.5% of a tetrapolymer, 0.1-0.3% of a heavy oil penetrant, 0.3-1% of a surfactant, and the balance of water; The surfactant includes lipopeptide biosurfactant and sodium fatty alcohol polyoxyethylene ether carboxylate; The quaternary copolymer is obtained by copolymerizing acrylamide, acryloylmorpholine, 2-acrylamide-2-methylpropanesulfonic acid and hexadecyldimethylallylammonium chloride; The thick oil penetrant is octadecyl methacrylate or octadecyl acrylate.

[0008] Optionally, the mass ratio of the lipopeptide biosurfactant to sodium fatty alcohol polyoxyethylene ether carboxylate is 1:1-1.5.

[0009] Optionally, the lipopeptide biosurfactant is a cyclic lipopeptide composed of β-hydroxy fatty acid and 7 amino acids, the fatty acid portion is normal, isomeric and trans isomeric fatty acids with a carbon chain length of 7 to 10, and the connection sequence of the amino acid portion is Glu-Leu-Leu-Val-Asp-Leu-Leu.

[0010] Optionally, the method for preparing the tetrapolymer comprises the following steps: (1) Dissolve acrylamide, acryloylmorpholine, 2-acrylamide-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride in water, with the mass fraction of the polymerizable monomer being 30-35%, stir until completely dissolved, adjust the pH to 7, and pass nitrogen to remove oxygen; (2) adding an initiator dropwise, stirring evenly, passing nitrogen to remove oxygen, causing a polymerization reaction to occur, and obtaining a colloidal polymer; (3) Cut the colloidal polymer into pieces, wash, soak and dry it with anhydrous ethanol to obtain a tetrapolymer.

[0011] Optionally, the mass ratio of acrylamide, acryloylmorpholine, 2-acrylamide-2-methylpropanesulfonic acid and hexadecyldimethylallylammonium chloride is (7-10):(8-10):(1-3):(1-2).

[0012] Optionally, the initiator is a mixture of potassium persulfate and sodium bisulfite; the mass ratio of potassium persulfate to sodium bisulfite is 1:1-2.

[0013] Optionally, the reaction temperature of the polymerization reaction in step (2) is 20-25° C., and the reaction time is 5-6 h.

[0014] According to another aspect of the present application, a tertiary oil recovery method using the above-mentioned composite oil displacement agent is also provided, comprising the following steps: (1) Select the layer section for tertiary oil recovery in the target well and divide the layer section into 3-5 groups of intake section and discharge section; (2) Lower the packer and production pipe into the target well; (3) Injecting the injection fluid containing the composite oil displacement agent into each swallowing section and then shutting down the well; (4) After the well is soaked, the oil-water mixture displaced by the injected fluid is produced from each discharge section.

[0015] Optionally, in step (3), the volume ratio of the injection fluid to the fracturing fluid is 1:5-6; and the mass ratio of the composite oil displacement agent to the injection fluid is 0.5-2:100.

[0016] Optionally, the soaking time is 5-8 days.

[0017] The beneficial effects of this application include but are not limited to: 1. A composite oil displacement agent according to the present application can improve oil displacement efficiency by compounding a specific tetrapolymer, a surfactant and a heavy oil penetrant in a specific ratio, and the oil displacement agent has salt and high temperature resistance, and can meet the requirements of high-efficiency viscosity increase under high temperature and high mineralization conditions.

[0018] 2. A composite oil displacement agent according to the present application is prepared by compounding a specific lipopeptide surfactant with sodium polyoxyethylene alcohol ether carboxylate in a specific ratio to obtain a surfactant; wherein the lipopeptide surfactant effectively increases the degradation rate of oil, especially the degradation of aromatic hydrocarbons, non-hydrocarbons and asphaltene components; sodium polyoxyethylene alcohol ether carboxylate can effectively reduce interfacial tension, and it has the characteristics of anionic and nonionic surfactants, can have relatively strong stability and emulsification ability under high salinity, and can interact with the quaternary polymer to improve the sweep and oil washing efficiency.

[0019] 3. According to a composite oil displacement agent of the present application, by making specific restrictions on monomer types, monomer ratios, initiators, etc., a quaternary polymer is obtained, and the quaternary polymer contains morpholine ring rigid groups, sulfonic acid groups and associative groups. Since there is no π-π conjugation in the acryloylmorpholine molecule, the activity of the monomer free radicals during polymerization is stronger and it is easier to copolymerize with other olefin monomers; the morpholine ring can also improve the water solubility and viscosity-increasing ability of the copolymer through intermolecular hydrogen bonding. The polymer can adapt to high-temperature and high-salinity oil reservoir conditions, cooperate with specific surfactants to improve oil displacement efficiency and achieve increased production.

[0020] 4. According to the tertiary oil recovery method using a composite oil-displacing agent of the present application, the construction process is simplified, the construction period is shortened, and multiple well opening and closing are not required, and the energy of the reservoir will not be supplemented; the injection fluid containing the composite oil-displacing agent is injected from the swallowing section, which can greatly increase the scope of action of the oil-displacing agent and achieve the effect of increasing production; and the ratio of the injection fluid, the fracturing fluid, and the composite oil-displacing agent is specifically limited to achieve a better oil displacement effect. DETAILED DESCRIPTION

[0021] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0022] Unless otherwise defined, all professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. The reagents or raw materials used in the present invention can be purchased through conventional channels. Unless otherwise specified, the reagents or raw materials used in the present invention are used in a conventional manner in the art or in accordance with the product instructions. In addition, any method and material similar or equivalent to the described content can be applied to the method of the present invention. The preferred implementation methods and materials described in this patent are for demonstration purposes only.

[0023] Example 1 (1) Select the layer section for tertiary oil recovery in the target well and divide the layer section into three groups of intake section and discharge section; (2) Lower the packer and production pipe into the target well; (3) Injecting the injection fluid containing the composite oil-displacing agent into each swallowing section, the volume ratio of the injection fluid to the fracturing fluid is 1:5, and the mass ratio of the composite oil-displacing agent to the injection fluid is 0.5:100, and the well is kept incubated for 5 days; (4) After the well is soaked, the oil-water mixture displaced by the injected fluid is produced from each discharge section.

[0024] A composite oil displacement agent, comprising 0.5% of a tetrapolymer, 0.1% of a heavy oil penetrant octadecyl methacrylate, 0.3% of a surfactant and the remainder of water; the surfactant comprises a lipopeptide biosurfactant and sodium polyoxyethylene fatty alcohol ether carboxylate, the mass ratio of the lipopeptide biosurfactant to the sodium polyoxyethylene fatty alcohol ether carboxylate being 1:1; the lipopeptide biosurfactant is a cyclic lipopeptide composed of β-hydroxy fatty acid and 7 amino acids, the fatty acid portion is normal, isomeric and trans-isomer fatty acids with a carbon chain length of 7 to 10, and the connection sequence of the amino acid portion is Glu-Leu-Leu-Val-Asp-Leu-Leu; The preparation method of the tetrapolymer comprises the following steps: (1) Dissolve acrylamide, acrylamide morpholine, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyl dimethyl allyl ammonium chloride in water, wherein the mass fraction of the polymerizable monomer is 30 and the mass ratio of acrylamide, acrylamide morpholine, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyl dimethyl allyl ammonium chloride is 7:8:1:1, stir until completely dissolved, adjust the pH to 7, and pass nitrogen to remove oxygen; (2) adding a mixture of initiators potassium persulfate and sodium bisulfite dropwise, with a mass ratio of potassium persulfate to sodium bisulfite of 1:1, stirring evenly, passing nitrogen to deoxygenate, and causing a polymerization reaction at a reaction temperature of 20°C for 5 hours to obtain a colloidal polymer; (3) Cut the colloidal polymer into pieces, wash, soak and dry it with anhydrous ethanol to obtain a quaternary polymer.

[0025] Example 2 (1) Select the layer section for tertiary oil recovery in the target well and divide the layer section into five groups of intake section and discharge section; (2) Lower the packer and production pipe into the target well; (3) Injecting the injection fluid containing the composite oil-displacing agent into each swallowing section, the volume ratio of the injection fluid to the fracturing fluid is 1:6, the mass ratio of the composite oil-displacing agent to the injection fluid is 0.5:100, and the well is kept in a well for 8 days; (4) After the well is soaked, the oil-water mixture displaced by the injected fluid is produced from each discharge section.

[0026] A composite oil displacement agent, comprising 1.5% of a tetrapolymer, 0.3% of a heavy oil penetrant octadecyl methacrylate, 1% of a surfactant and the remainder of water; the surfactant comprises a lipopeptide biosurfactant and sodium fatty alcohol polyoxyethylene ether carboxylate, the mass ratio of the lipopeptide biosurfactant to the sodium fatty alcohol polyoxyethylene ether carboxylate being 1:1.5; the lipopeptide biosurfactant is a cyclic lipopeptide composed of β-hydroxy fatty acid and 7 amino acids, the fatty acid portion is normal, isomeric and trans-isomerized fatty acids with a carbon chain length of 7 to 10, and the connection sequence of the amino acid portion is Glu-Leu-Leu-Val-Asp-Leu-Leu; The preparation method of the tetrapolymer comprises the following steps: (1) Dissolve acrylamide, acrylamide morpholine, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyl dimethyl allyl ammonium chloride in water, wherein the mass fraction of the polymerizable monomer is 35% and the mass ratio of acrylamide, acrylamide morpholine, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyl dimethyl allyl ammonium chloride is 10:10:3:2, stir until completely dissolved, adjust the pH to 7, and pass nitrogen to remove oxygen; (2) adding a mixture of initiators potassium persulfate and sodium bisulfite in a mass ratio of 1:2, stirring evenly, passing nitrogen to deoxygenate, and causing a polymerization reaction at a reaction temperature of 25°C for 6 hours to obtain a colloidal polymer; (3) Cut the colloidal polymer into pieces, wash, soak and dry it with anhydrous ethanol to obtain a quaternary polymer.

[0027] Example 3 (1) Select the layer section for tertiary oil recovery in the target well and divide the layer section into four groups of intake section and discharge section; (2) Lower the packer and production pipe into the target well; (3) Injecting the injection fluid containing the composite oil-displacing agent into each swallowing section, the volume ratio of the injection fluid to the fracturing fluid is 1:5.5, the mass ratio of the composite oil-displacing agent to the injection fluid is 1:100, and the well is kept in a well for 6 days; (4) After the well is soaked, the oil-water mixture displaced by the injected fluid is produced from each discharge section.

[0028] A composite oil displacement agent, comprising 1% of a tetrapolymer, 0.2% of a heavy oil penetrant octadecyl acrylate, 0.6% of a surfactant and the balance of water; the surfactant comprises a lipopeptide biosurfactant and sodium polyoxyethylene fatty alcohol ether carboxylate, the mass ratio of the lipopeptide biosurfactant to the sodium polyoxyethylene fatty alcohol ether carboxylate being 1:1.2; the lipopeptide biosurfactant is a cyclic lipopeptide composed of β-hydroxy fatty acid and 7 amino acids, the fatty acid portion is normal, isomeric and trans-isomer fatty acids with a carbon chain length of 7 to 10, and the connection sequence of the amino acid portion is Glu-Leu-Leu-Val-Asp-Leu-Leu; The preparation method of the tetrapolymer comprises the following steps: (1) Dissolve acrylamide, acrylamide morpholine, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyl dimethyl allyl ammonium chloride in water, wherein the mass fraction of the polymerizable monomer is 30% and the mass ratio of acrylamide, acrylamide morpholine, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyl dimethyl allyl ammonium chloride is 7:8:3:2, stir until completely dissolved, adjust the pH to 7, and pass nitrogen to remove oxygen; (2) adding a mixture of initiators potassium persulfate and sodium bisulfite in a mass ratio of 1:1.5, stirring evenly, passing nitrogen to deoxygenate, and causing a polymerization reaction at a reaction temperature of 22°C for 5.5 hours to obtain a colloidal polymer; (3) Cut the colloidal polymer into pieces, wash, soak and dry it with anhydrous ethanol to obtain a quaternary polymer.

[0029] Example 4 The difference between Example 4 and Example 3 is that the mass ratio of the composite oil-displacing agent to the injection liquid is 3:100, and the rest are the same.

[0030] Example 5 The difference between Example 5 and Example 3 is that the volume ratio of injection fluid to fracturing fluid is 1:10, and the rest are the same.

[0031] Comparative Example 1 The difference between Comparative Example 1 and Example 3 is that the composite oil-displacing agent in Comparative Example 1 does not include a quaternary polymer, and the rest are the same.

[0032] Comparative Example 2 The difference between Comparative Example 2 and Example 3 is that the surfactant in Comparative Example 2 does not include lipopeptide biosurfactant, and the rest are the same.

[0033] Comparative Example 3 The difference between Comparative Example 3 and Example 3 is that the mass ratio of the lipopeptide biosurfactant to the sodium alcohol polyoxyethylene ether carboxylate in Comparative Example 3 is 1:2, and the rest are the same.

[0034] Comparative Example 4 The difference between Comparative Example 4 and Example 3 is that the surfactant in Comparative Example 4 does not include sodium alcohol polyoxyethylene ether carboxylate, and the rest is the same.

[0035] Comparative Example 5 The difference between Comparative Example 5 and Example 3 is that the composite oil displacement agent in Comparative Example 5 does not include a heavy oil penetrant, and the rest are the same.

[0036] Comparative Example 6 The difference between Comparative Example 6 and Example 3 is that the mass ratio of acrylamide, acrylamide morpholine, 2-acrylamide-2-methylpropane sulfonic acid and hexadecyldimethylallylammonium chloride in Comparative Example 6 is 6:11:2:1, and the rest are the same.

[0037] Comparative Example 7 The difference between Comparative Example 7 and Example 3 is that the mass fraction of the polymerized monomer in Comparative Example 7 is 40%, and the rest are the same.

[0038] Comparative Example 8 The difference between Comparative Example 8 and Example 3 is that the mass ratio of potassium persulfate to sodium bisulfite in Comparative Example 8 is 1:3, and the rest are the same.

[0039] Experimental Example 1 The composite oil displacement agents obtained in Examples 1 to 5 and Comparative Examples 1 to 8 were subjected to performance tests according to SY / T 6424-2014 “Composite Oil Displacement System Performance Test Method”. The test results are shown in Table 1.

[0040] Table 1 Performance test results

[0041] According to Table 1, the interfacial tension and oil removal efficiency of the composite oil-displacing agent obtained in Examples 1 to 3 are both high, wherein Example 3 is the best example, Example 4 changes the mass ratio of the composite oil-displacing agent to the injection fluid, and Example 5 changes the volume ratio of the injection fluid to the fracturing fluid, and the oil displacement efficiency decreases to varying degrees compared with Example 3; in Comparative Examples 1 to 5, the components or ratios of the composite oil-displacing agent are changed, and the interfacial tension increases to varying degrees, while the oil displacement efficiency decreases to varying degrees, wherein the decrease in Comparative Example 1 is the most obvious; in Comparative Examples 6 to 8, in the process of preparing the quaternary copolymer, the mass ratio of each monomer, the mass fraction of the polymerized monomer, and the ratio of the initiator are changed, and the interfacial tension of the obtained composite oil-displacing agent increases, while the oil displacement efficiency decreases.

[0042] The above is only the embodiment of the present application, and the protection scope of the present application is not limited by these specific embodiments, but is determined by the claims of the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the technical ideas and principles of the present application should be included in the protection scope of the present application.

Claims

1. A composite oil displacement agent, It is characterized in that The composition comprises the following percentages: 0.5-1.5% of tetrapolymer, 0.1-0.3% of heavy oil penetrant, 0.3-1% of surfactant and the balance of water; The surfactant includes lipopeptide biosurfactant and sodium fatty alcohol polyoxyethylene ether carboxylate; The quaternary copolymer is obtained by copolymerizing acrylamide, acryloylmorpholine, 2-acrylamide-2-methylpropanesulfonic acid and hexadecyldimethylallylammonium chloride; The thick oil penetrant is octadecyl methacrylate or octadecyl acrylate.

2. A composite oil-displacing agent according to claim 1, It is characterized in that The mass ratio of the lipopeptide biosurfactant to sodium fatty alcohol polyoxyethylene ether carboxylate is 1:1-1.

5.

3. A composite oil-displacing agent according to claim 1, It is characterized in that The lipopeptide biosurfactant is a cyclic lipopeptide composed of β-hydroxy fatty acid and 7 amino acids, the fatty acid part is normal, isomeric and trans isomeric fatty acids with a carbon chain length of 7 to 10, and the connection sequence of the amino acid part is Glu-Leu-Leu-Val-Asp-Leu-Leu.

4. A composite oil-displacing agent according to claim 1, It is characterized in that The preparation method of the tetrapolymer comprises the following steps: (1) Dissolve acrylamide, acryloylmorpholine, 2-acrylamide-2-methylpropanesulfonic acid and hexadecyldimethylallyl ammonium chloride in water, with the mass fraction of the polymerizable monomer being 30-35%, stir until completely dissolved, adjust the pH to 7, and pass nitrogen to remove oxygen; (2) adding an initiator dropwise, stirring evenly, passing nitrogen to remove oxygen, causing a polymerization reaction to occur, and obtaining a colloidal polymer; (3) Cut the colloidal polymer into pieces, wash, soak and dry it with anhydrous ethanol to obtain a tetrapolymer.

5. A composite oil-displacing agent according to claim 4, It is characterized in that The mass ratio of acrylamide, acryloylmorpholine, 2-acrylamide-2-methylpropanesulfonic acid and hexadecyldimethylallylammonium chloride is (7-10):(8-10):(1-3):(1-2).

6. A composite oil-displacing agent according to claim 4, It is characterized in that The initiator is a mixture of potassium persulfate and sodium bisulfite; the mass ratio of potassium persulfate to sodium bisulfite is 1:1-2.

7. A composite oil-displacing agent according to claim 4, It is characterized in that The reaction temperature of the polymerization reaction in step (2) is 20-25° C., and the reaction time is 5-6 h.

8. A tertiary oil recovery method using the composite oil displacement agent according to any one of claims 1 to 7, It is characterized in that The following steps are involved: (1) Select the layer section for tertiary oil recovery in the target well and divide the layer section into 3-5 groups of intake section and discharge section; (2) Lower the packer and production pipe into the target well; (3) Injecting the injection fluid containing the composite oil displacement agent into each swallowing section and then shutting down the well; (4) After the well is soaked, the oil-water mixture displaced by the injected fluid is produced from each discharge section.

9. The tertiary oil recovery method using a composite oil displacement agent according to claim 8, It is characterized in that In step (3), the volume ratio of the injection fluid to the fracturing fluid is 1:5-6; the mass ratio of the composite oil displacement agent to the injection fluid is 0.5-2:

100.

10. The tertiary oil recovery method using a composite oil displacement agent according to claim 8, It is characterized in that The soaking time is 5-8 days.

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