Solid surfactant as well as preparation method and application thereof

Abstract

The invention relates to a solid surfactant as well as a preparation method and application thereof. The invention relates to a solid surfactant, which is prepared from modified starch and biological enzyme in parts by mass, and the structural formula of the modified starch is R2O-(CH2CH2CH2O) n-St-(OCH2CH2) mOR1, or St-(OCH2CH2) mOR1, or St-(OCH2CH2CH2) nOR2. The invention also discloses a preparation method of the solid surfactant. The preparation method comprises the following steps: (1) grafting hydrophilic and hydrophobic groups on starch to obtain modified starch; and (2) uniformly stirring the modified starch according to the formula ratio, the biological enzyme according to the formula ratio and a proper amount of water, carrying out compression molding, demolding and drying to obtain the solid surfactant. The invention also discloses the solid surfactant and application of the solid surfactant prepared by the preparation method as an injection-increasing oil-displacing agent in oil exploitation.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield water injection development, and in particular to a solid surfactant and a preparation method and application thereof. Background Art

[0002] The water-drive reservoirs of Shengli Oilfield include monolithic, fault-block, and low-permeability reservoirs, which are the cornerstone of the stable development of the oilfield. However, the following problems exist in the development of onshore water-drive reservoirs: the development degree of onshore water-drive reservoirs varies greatly, there are many inefficient units, low production capacity, and high costs. The main reasons are: first, the inefficient unit reservoirs have strong heterogeneity, small water sweep volume, and uneven displacement, resulting in low water drive efficiency; second, the formation pressure is maintained at a low level, the water injection pressure is high, resulting in low production and high costs; third, the inefficient unit reservoirs have strong oil / solid interface effects, large adhesion work, high water content (>93%), and more residual oil. It is difficult to strip crude oil from micro-nano pores, and the water drive system operates inefficiently. In order to solve the above problems in the development of water-drive reservoirs, the currently disclosed technical routes mainly include two categories: pressure reduction and injection system and oil displacement surfactant system.

[0003] The first category: the pressure reduction and injection system is mainly divided into two subcategories. The first subcategory is the pressure reduction and injection system containing nano-silicon dioxide. For example, Chinese patent CN112552893B discloses a molecular membrane pressure reduction and injection surfactant and its preparation method. A molecular membrane pressure reduction and injection surfactant comprises 15-25 parts of tea saponin modified betaine surfactant, 35-50 parts of nano-silicon dioxide, and 25-40 parts of metal oxide powder. Chinese invention patent application CN106085401A discloses a pressure reduction and injection agent for low permeability oil field water injection wells and its preparation method and application. The pressure reducing and injection enhancing agent is prepared from the following components by weight percentage: 2.0% to 6.5% of a multifunctional surface treatment agent, 0.75% to 3.15% of hydrophobic nano-silicon dioxide or nano-polysilicon, 2% to 8% of a pH adjusting agent, and the rest is deionized water; the multifunctional surface treatment agent is composed of the following components by weight percentage: 30% to 80% of a nonionic surfactant, 2% to 25% of anionic surfactant, and 10% to 50% of an amphoteric surfactant. The second subcategory is a surfactant pressure reducing and injection enhancing system, such as the Chinese invention patent CN111944506B which discloses a pressure reducing and injection enhancing active agent and a preparation method thereof. The pressure reducing and injection enhancing active agent system is composed of long-chain fatty acid diethanolamide, anionic surfactant, cationic surfactant, nanomaterial (at least one of oleophilic modified graphene oxide, montmorillonite, and silica), an auxiliary agent, and water. The Chinese invention patent CN101538461B discloses a pressure reducing and injection enhancing agent for water injection wells and a preparation method thereof. A pressure reducing and injection-increasing agent for water injection wells, wherein the weight ratios of the components are: lauric acid monoethanolamide: 30 to 42 parts; L-valine benzyl p-toluenesulfonate: 2.5 to 4.5 parts; C 8-10 alkyl glucoside: 5.5 to 7.5 parts; sodium nitrite: 0.5 to 1.0 parts; vitamin A: 0.5 to 1 parts; fluorocarbon surfactant FN-2: 0.05 to 0.1 parts; methanol: 25 to 35 parts; and water: 15 to 35 parts.

[0004] The second category: oil recovery surfactant system, such as Chinese invention patent CN106010494B provides a low permeability oil reservoir recovery surfactant and its preparation and product. The method comprises: using an organic solvent as a reaction solvent, reacting a nonionic surfactant and a glycidyl ether compound as raw materials in the presence of an alkaline catalyst to obtain a reaction solution, hydrolyzing the reaction solution in the presence of a pH regulator, and then reacting with a metal organic salt under alkaline conditions to obtain the low permeability oil reservoir recovery surfactant; wherein the molar ratio of the nonionic surfactant, the glycidyl ether compound, the metal organic salt, the alkaline catalyst and the pH regulator is 8:4:4:1:2. Chinese invention patent CN104371689B discloses an ultra-low interfacial tension surfactant compound system and its preparation method, an ultra-low interfacial tension surfactant compound system, in terms of mass percentage, including 10% to 33% of amphoteric surfactants, 7% to 23% of nonionic surfactants, 1% to 4% of anionic surfactants, and the balance is water.

[0005] In summary, the current pressure reduction and injection enhancement systems and oil displacement surfactant systems are mainly nanosystems, conventional liquid surfactants and their compositions, and their use method is mainly to inject them into the well using a pump truck or a plunger pump. They have the following disadvantages: 1. The operation time is relatively long; 2. Pump trucks or plunger pump equipment are required, and the operation cost is high. Summary of the invention

[0006] Purpose of the invention: The purpose of the present invention is to provide a solid surfactant and its preparation method and application. The solid surfactant of the present invention can be put into the water injection process or the bottom of the wellbore at one time, and slowly hydrolyzes and releases the alkyl glycoside alcohol ether surfactant in the water injected into the wellbore or downhole, without the need for continuous pumping by a pump truck or a plunger pump, which greatly shortens the well shut-in time, saves operation time and operation costs, and saves the pump truck or plunger pump pumping manual dosing and maintenance costs. The alkyl glycoside alcohol ether surfactant released after the hydrolysis of the solid surfactant can reduce the oil-water interfacial tension to 1.0×10 -3 mN / m, remove residual oil, reduce capillary resistance, and achieve the purpose of reducing pressure and increasing injection; at the same time, strengthen oil washing, improve microwave and, achieve the purpose of improving recovery rate.

[0007] Technical solution: A solid surfactant, calculated by weight, is composed of the following components;

[0008] 100 parts of modified starch, 10-120 parts of biological enzymes, including:

[0009] The structural formula of modified starch is: R2O-(CH2CH2CH2O) n -St-(OCH2CH2) m OR1, either:

[0010] St-(OCH2CH2) m OR1, either:

[0011] St-(OCH2CH2CH2) n OR2, where:

[0012] St is a starch molecule, m is a positive integer, and 1≤m≤9; n is a positive integer, and 1≤n≤9; R1 is a straight chain alkyl or branched chain alkyl of 8 to 16 carbon atoms, and R2 is a straight chain alkyl or branched chain alkyl of 8 to 16 carbon atoms.

[0013] Furthermore, the biological enzyme is amylase and / or maltase.

[0014] Furthermore, the amylase is one or more of mesophilic amylase, thermophilic amylase, isoamylase and saccharifying enzyme.

[0015] A method for preparing any of the above-mentioned solid surfactants, comprising the following specific steps:

[0016] (1) Grafting hydrophilic and hydrophobic groups onto starch to obtain modified starch;

[0017] (2) After uniformly mixing the modified starch in the formula amount, the biological enzyme in the formula amount and an appropriate amount of water, the mixture is molded, demolded and dried to obtain a solid surfactant.

[0018] Further, in parts by mass, step (1) comprises the following steps:

[0019] (11), taking 20 to 160 parts of an organic solvent into a reaction container, then adding 36 to 40 parts of starch and 2 to 9 parts of a solid acid resin catalyst into the reaction container under stirring, and then activating at 25 to 55° C. for at least 2 hours to obtain a mixed solution;

[0020] (12) adding 26 to 280 parts of fatty alcohol ether to the mixed solution obtained in step (11), heating to 50 to 130° C. and stirring while performing etherification reaction for 8 to 24 hours to obtain a reaction solution;

[0021] (13) Filter the reaction solution obtained in step (12), take the filtrate, neutralize the filtrate with an alkaline substance, and perform vacuum distillation to remove most of the organic solvent to a solid sample, which is then transferred to a vacuum drying oven and dried under low temperature to obtain the modified starch.

[0022] Furthermore, the organic solvent in step (11) is one or more of isopropanol, dimethyl sulfoxide, acetonitrile and dimethylformamide.

[0023] Furthermore, the organic solvent in step (11) is a mixed solution of isopropanol and dimethyl sulfoxide, wherein:

[0024] The mass ratio of isopropanol to dimethyl sulfoxide is (1-3):(1-5).

[0025] Furthermore, the starch in step (11) is dried before being added.

[0026] Furthermore, the starch in step (11) is one or more of corn starch, potato starch, wheat starch, cassava starch, sweet potato starch, sorghum starch, and rice starch.

[0027] Furthermore, the solid acid resin catalyst in step (11) is a resin catalyst with a sulfonic acid group, specifically one of Amberlyst 15dry catalyst, NKC-9 resin catalyst (Elester (Shanghai) New Material Technology Co., Ltd.) or solid acid catalyst resin T-63MP (Kohais Co., Ltd.).

[0028] Furthermore, the fatty alcohol ether in step (12) is one or more of fatty alcohol polyoxyethylene ether and fatty alcohol polyoxypropylene ether.

[0029] Furthermore, the molecular formula of the fatty alcohol polyoxyethylene ether is: R1O(CH2CH2O) m H, where:

[0030] m is a positive integer, and 1≤m≤9, and R1 is a straight chain alkyl or branched chain alkyl having 8 to 16 carbon atoms.

[0031] Furthermore, the molecular formula of the fatty alcohol polyoxypropylene ether is: R2O(CH2CH2CH2O) n H, where:

[0032] n is a positive integer, and 1≤n≤9, and R2 is a straight chain alkyl or branched chain alkyl having 8 to 16 carbon atoms.

[0033] Furthermore, the fatty alcohol ether in step (12) is added dropwise at a rate of 1 to 10 drops per second.

[0034] Further, in parts by mass, step (2) comprises the following steps:

[0035] (21) Dissolve the modified starch in a formula amount into a paste with an appropriate amount of water, then add the biological enzyme in a formula amount, and stir evenly to obtain a mixture, wherein:

[0036] The mass ratio of modified starch to water is 100:(5-50);

[0037] (22) The mixture obtained in step (21) is molded using a mold, and after demolding and drying, a solid surfactant is obtained.

[0038] Furthermore, the water added in step (21) is in liquid state and has a water temperature below 25°C.

[0039] Furthermore, the solid surfactant obtained in step (22) is in the shape of a rod, a block, a granule, or a honeycomb.

[0040] Any of the above solid surfactants or the solid surfactant prepared by any of the above preparation methods is used as an injection and displacement agent in petroleum production.

[0041] Usage: Directly put the solid surfactant into the process pipeline or into the bottom of the well during operation. At the injection water temperature, the modified starch is decomposed into an alcohol ether glycoside surfactant with a polymerization degree of 1-2 under the action of different biological enzymes, which plays a role in reducing pressure and increasing injection, improving microwave and oil washing efficiency, and ultimately improving the effect of water flooding development. The method of use is simple and convenient, and no operation and pumping equipment are required.

[0042] Beneficial effects: The solid surfactant disclosed in the present invention and its preparation method and application have the following advantages:

[0043] Beneficial effects:

[0044] 1. The operation time is shorter;

[0045] 2. No supporting equipment such as pump trucks or plunger pumps is required, and the operating cost is low;

[0046] 3. The operation method is simple and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The present invention discloses a flow chart of a method for preparing a solid surfactant. DETAILED DESCRIPTION

[0048] The specific embodiments of the present invention are described in detail below.

[0049] In the present application: the effective temperature of medium-temperature amylase is 60-90°C, the effective temperature of high-temperature amylase is 55-110°C, and the effective temperature of isoamylase is 50-70°C.

[0050] A method for preparing a solid surfactant, the specific steps are as follows:

[0051] (1) Grafting hydrophilic and hydrophobic groups onto starch to obtain modified starch, which has surface and interfacial activity after hydrolysis, thus achieving the purpose of increasing oil displacement;

[0052] (2) After uniformly mixing the modified starch in the formula amount, the biological enzyme in the formula amount and an appropriate amount of water, the mixture is molded and dried to obtain a solid surfactant.

[0053] Taking amylose and polyoxyethylene ether as examples, the synthesis of fatty alcohol ether modified starch is as follows:

[0054]

[0055] The following examples are provided for detailed description. The following examples are only for illustration purposes and the present invention is by no means limited to the following examples.

[0056] Example 1

[0057] A solid surfactant, comprising the following components in parts by mass:

[0058] 100 parts of modified starch, 60 parts of biological enzymes, including:

[0059] The structural formula of modified starch is: R2O-(CH2CH2CH2O) n -St-(OCH2CH2) m OR1, where:

[0060] St is a starch molecule, m is 4, n is 5, R1 is a straight-chain alkyl group with 10 carbon atoms, and R2 is a straight-chain alkyl group with 9 carbon atoms.

[0061] Furthermore, the biological enzyme is a mixture of amylase and maltase in equal mass ratio.

[0062] Furthermore, the amylase is a mesophilic amylase. In another embodiment, the amylase is a mixture of an equal mass ratio of a mesophilic amylase, a high temperature amylase and a saccharifying enzyme. In another embodiment, the amylase is a high temperature amylase. In another embodiment, the amylase is an isoamylase. In another embodiment, the amylase is a saccharifying enzyme.

[0063] A method for preparing the above-mentioned solid surfactant comprises the following specific steps:

[0064] (1) Grafting hydrophilic and hydrophobic groups onto starch to obtain modified starch;

[0065] (2) After uniformly mixing the modified starch in the formula amount, the biological enzyme in the formula amount and an appropriate amount of water, the mixture is molded, demolded and dried to obtain a solid surfactant.

[0066] Further, in parts by mass, step (1) comprises the following steps:

[0067] (11), taking 20 parts of an organic solvent into a reaction container, then adding 36 parts of starch and 2 parts of a solid acid resin catalyst into the reaction container under stirring, and then activating at 25° C. for 12 hours to obtain a mixed solution;

[0068] (12) Add 26 parts of fatty alcohol ether to the mixed solution obtained in step (11), raise the temperature to 50° C., and carry out etherification reaction for 24 hours while stirring to obtain a reaction solution;

[0069] (13) Filter the reaction solution obtained in step (12), take the filtrate, neutralize the filtrate with an alkaline substance, and perform vacuum distillation to remove most of the organic solvent to a solid sample, which is then transferred to a vacuum drying oven and dried under low temperature to obtain the modified starch.

[0070] Further, the organic solvent in step (11) is a mixed solution of isopropanol and dimethyl sulfoxide, wherein the mass ratio of isopropanol to dimethyl sulfoxide is 1:1. In another embodiment, the organic solvent in step (11) is isopropanol. In another embodiment, the organic solvent in step (11) is dimethyl sulfoxide. In another embodiment, the organic solvent in step (11) is acetonitrile. In another embodiment, the organic solvent in step (11) is dimethylformamide. In another embodiment, the organic solvent in step (11) is a mixture of isopropanol, dimethyl sulfoxide, acetonitrile and dimethylformamide in equal mass ratios.

[0071] Furthermore, the starch in step (11) is dried before being added.

[0072] Further, the starch described in step (11) is corn starch. In another embodiment, the starch described in step (11) is potato starch. In another embodiment, the starch described in step (11) is wheat starch. In another embodiment, the starch described in step (11) is tapioca starch. In another embodiment, the starch described in step (11) is sweet potato starch. In another embodiment, the starch described in step (11) is sorghum starch. In another embodiment, the starch described in step (11) is rice starch. In another embodiment, the starch described in step (11) is a mixture of corn starch, potato starch, wheat starch, tapioca starch, sweet potato starch, sorghum starch and rice starch in equal mass ratios.

[0073] Furthermore, the solid acid resin catalyst in step (11) is a resin catalyst having a sulfonic acid group, specifically Amberlyst 15dry catalyst.

[0074] Furthermore, the fatty alcohol ether in step (12) is a mixture of fatty alcohol polyoxyethylene ether and fatty alcohol polyoxypropylene ether.

[0075] Furthermore, the molecular formula of the fatty alcohol polyoxyethylene ether is: R1O(CH2CH2O) m H, where:

[0076] m is 4, and R1 is a straight-chain alkyl group having 10 carbon atoms.

[0077] Furthermore, the molecular formula of the fatty alcohol polyoxypropylene ether is: R2O(CH2CH2CH2O) n H, where:

[0078] n is 5, and R2 is a straight chain alkyl group of 9 carbon atoms.

[0079] Furthermore, the fatty alcohol ether in step (12) is added dropwise at a rate of 5 drops per second.

[0080] Further, in parts by mass, step (2) comprises the following steps:

[0081] (21) Dissolve the modified starch in a formula amount into a paste with an appropriate amount of water, then add the biological enzyme in a formula amount, and stir evenly to obtain a mixture, wherein:

[0082] The mass ratio of modified starch to water is 100:5;

[0083] (22) The mixture obtained in step (21) is molded using a mold, and after demolding and drying, a solid surfactant is obtained.

[0084] Furthermore, the water added in step (21) is in liquid state and has a water temperature below 25°C.

[0085] Furthermore, the solid surfactant obtained in step (22) is in the shape of a rod. In another embodiment, the solid surfactant obtained in step (22) is in the shape of a block. In another embodiment, the solid surfactant obtained in step (22) is in the shape of a granule. In another embodiment, the solid surfactant obtained in step (22) is in the shape of a honeycomb.

[0086] Any of the above solid surfactants or the solid surfactant prepared by any of the above preparation methods is used as an injection and displacement agent in petroleum production.

[0087] Example 2

[0088] It is substantially the same as Example 1, except that:

[0089] A solid surfactant, comprising the following components in parts by mass:

[0090] 100 parts of modified starch, 10 parts of biological enzyme, including:

[0091] The structural formula of modified starch is: R2O-(CH2CH2CH2O) n -St-(OCH2CH2) m OR1, where:

[0092] St is a starch molecule, m is 1, n is 9, R1 is a branched alkyl group with 8 carbon atoms, and R2 is a straight-chain alkyl group with 16 carbon atoms.

[0093] Example 3

[0094] It is substantially the same as Example 1, except that:

[0095] A solid surfactant, comprising the following components in parts by mass:

[0096] 100 parts of modified starch, 120 parts of biological enzymes, including:

[0097] The structural formula of modified starch is: R2O-(CH2CH2CH2O) n -St-(OCH2CH2) m OR1, where:

[0098] St is a starch molecule, m is 9; n is 1; R1 is a branched alkyl group with 16 carbon atoms, and R2 is a branched alkyl group with 8 carbon atoms.

[0099] Example 4

[0100] A solid surfactant, comprising the following components in parts by mass:

[0101] 100 parts of modified starch, 60 parts of biological enzymes, including:

[0102] The structural formula of modified starch is: St-(OCH2CH2) m OR1, where:

[0103] St is a starch molecule, m is 5; and R1 is a straight-chain alkyl group with 12 carbon atoms.

[0104] Furthermore, the biological enzyme is maltase.

[0105] A method for preparing the above-mentioned solid surfactant comprises the following specific steps:

[0106] (1) Grafting hydrophilic and hydrophobic groups onto starch to obtain modified starch;

[0107] (2) After uniformly mixing the modified starch in the formula amount, the biological enzyme in the formula amount and an appropriate amount of water, the mixture is molded, demolded and dried to obtain a solid surfactant.

[0108] Further, in parts by mass, step (1) comprises the following steps:

[0109] (11), taking 160 parts of an organic solvent into a reaction container, then adding 40 parts of starch and 9 parts of a solid acid resin catalyst into the reaction container under stirring, and then activating at 55° C. for 2 hours to obtain a mixed solution;

[0110] (12) Add 280 parts of fatty alcohol ether to the mixed solution obtained in step (11), raise the temperature to 130° C., and carry out etherification reaction for 8 hours while stirring to obtain a reaction solution;

[0111] (13) Filter the reaction solution obtained in step (12), take the filtrate, neutralize the filtrate with an alkaline substance, and perform vacuum distillation to remove most of the organic solvent to a solid sample, which is then transferred to a vacuum drying oven and dried under low temperature to obtain the modified starch.

[0112] Furthermore, the organic solvent in step (11) is a mixed solution of isopropanol and dimethyl sulfoxide, wherein:

[0113] The mass ratio of isopropanol to dimethyl sulfoxide is 3:5.

[0114] Furthermore, the starch in step (11) is dried before being added.

[0115] Furthermore, the starch in step (11) is potato starch.

[0116] Furthermore, the solid acid resin catalyst in step (11) is a resin catalyst with a sulfonic acid group, specifically an NKC-9 resin catalyst (produced by Elest (Shanghai) New Material Technology Co., Ltd.).

[0117] Furthermore, the fatty alcohol ether in step (12) is one or more of fatty alcohol polyoxyethylene ether and fatty alcohol polyoxypropylene ether.

[0118] Furthermore, the molecular formula of the fatty alcohol polyoxyethylene ether is: R1O(CH2CH2O) m H, where:

[0119] m is 5, and R1 is a linear or branched alkyl group with 12 carbon atoms.

[0120] Furthermore, the fatty alcohol ether in step (12) is added dropwise at a rate of 1 drop per second.

[0121] Further, in parts by mass, step (2) comprises the following steps:

[0122] (21) Dissolve the modified starch in a formula amount into a paste with an appropriate amount of water, then add the biological enzyme in a formula amount, and stir evenly to obtain a mixture, wherein:

[0123] The mass ratio of modified starch to water is 100:50;

[0124] (22) The mixture obtained in step (21) is molded using a mold, and after demolding and drying, a solid surfactant is obtained.

[0125] Furthermore, the water added in step (21) is in liquid state and has a water temperature below 25°C.

[0126] Furthermore, the solid surfactant obtained in step (22) has a honeycomb shape.

[0127] Any of the above solid surfactants or the solid surfactant prepared by any of the above preparation methods is used as an injection and displacement agent in petroleum production.

[0128] Example 5

[0129] It is substantially the same as Example 4, except that:

[0130] A solid surfactant, comprising the following components in parts by mass:

[0131] 100 parts of modified starch, 10 parts of biological enzyme, including:

[0132] The structural formula of modified starch is: St-(OCH2CH2) m OR1, where:

[0133] St is a starch molecule, m is 1; and R1 is a branched alkyl group with 8 carbon atoms.

[0134] Example 6

[0135] It is substantially the same as Example 4, except that:

[0136] A solid surfactant, comprising the following components in parts by mass:

[0137] 100 parts of modified starch, 120 parts of biological enzymes, including:

[0138] The structural formula of modified starch is: St-(OCH2CH2) m OR1, where:

[0139] St is a starch molecule, m is 9; and R1 is a branched alkyl group with 16 carbon atoms.

[0140] Example 7

[0141] A solid surfactant, comprising the following components in parts by mass:

[0142] 100 parts of modified starch, 25 parts of biological enzymes, including:

[0143] The structural formula of modified starch is: St-(OCH2CH2CH2) n OR2, where:

[0144] St is a starch molecule, n is 6; and R2 is a straight-chain alkyl group with 12 carbon atoms.

[0145] Furthermore, the biological enzyme is amylase.

[0146] Furthermore, the amylase is isoamylase.

[0147] A method for preparing any of the above-mentioned solid surfactants, comprising the following specific steps: (1) grafting hydrophilic and hydrophobic groups onto starch to obtain modified starch;

[0148] (2) After uniformly mixing the modified starch in the formula amount, the biological enzyme in the formula amount and an appropriate amount of water, the mixture is molded, demolded and dried to obtain a solid surfactant.

[0149] Further, in parts by mass, step (1) comprises the following steps:

[0150] (11), taking 100 parts of an organic solvent into a reaction container, then adding 38 parts of starch and 5 parts of a solid acid resin catalyst into the reaction container under stirring, and then activating at 30° C. for 6 hours to obtain a mixed solution;

[0151] (12) Add 100 parts of fatty alcohol ether to the mixed solution obtained in step (11), heat to 80° C., and carry out etherification reaction for 12 hours while stirring to obtain a reaction solution;

[0152] (13) Filter the reaction solution obtained in step (12), take the filtrate, neutralize the filtrate with an alkaline substance, and perform vacuum distillation to remove most of the organic solvent to a solid sample, which is then transferred to a vacuum drying oven and dried under low temperature to obtain the modified starch.

[0153] Furthermore, the organic solvent in step (11) is a mixed solution of isopropanol and dimethyl sulfoxide, wherein:

[0154] The mass ratio of isopropanol to dimethyl sulfoxide is 2:4.

[0155] Furthermore, the starch in step (11) is dried before being added.

[0156] Furthermore, the starch in step (11) is tapioca starch.

[0157] Furthermore, the solid acid resin catalyst in step (11) is a resin catalyst having a sulfonic acid group, specifically a solid acid catalyst resin T-63MP (produced by Kehaisi Co., Ltd.).

[0158] Furthermore, the fatty alcohol ether in step (12) is fatty alcohol polyoxypropylene ether.

[0159] Furthermore, the molecular formula of the fatty alcohol polyoxypropylene ether is: R2O(CH2CH2CH2O) n H, where:

[0160] n is 6, and R2 is a straight chain alkyl group having 12 carbon atoms.

[0161] Furthermore, the fatty alcohol ether in step (12) is added dropwise at a rate of 10 drops per second.

[0162] Further, in parts by mass, step (2) comprises the following steps:

[0163] (21) Dissolve the modified starch in a formula amount into a paste with an appropriate amount of water, then add the biological enzyme in a formula amount, and stir evenly to obtain a mixture, wherein:

[0164] The mass ratio of modified starch to water is 100:25;

[0165] (22) The mixture obtained in step (21) is molded using a mold, and after demolding and drying, a solid surfactant is obtained.

[0166] Furthermore, the water added in step (21) is in liquid state and has a water temperature below 25°C.

[0167] Furthermore, the solid surfactant obtained in step (22) is in the shape of a rod, a block, a granule, or a honeycomb.

[0168] Any of the above solid surfactants or the solid surfactant prepared by any of the above preparation methods is used as an injection and displacement agent in petroleum production.

[0169] Example 8

[0170] It is substantially the same as Example 7, except that:

[0171] A solid surfactant, comprising the following components in parts by mass:

[0172] 100 parts of modified starch, 10 parts of biological enzyme, including:

[0173] The structural formula of modified starch is: St-(OCH2CH2CH2) n OR2, where:

[0174] St is a starch molecule, n is 1; and R2 is a straight-chain alkyl group with 8 carbon atoms.

[0175] Example 9

[0176] It is substantially the same as Example 7, except that:

[0177] A solid surfactant, comprising the following components in parts by mass:

[0178] 100 parts of modified starch, 10-120 parts of biological enzymes, including:

[0179] The structural formula of modified starch is: St-(OCH2CH2CH2) n OR2, where:

[0180] St is a starch molecule, n is 9; and R2 is a branched alkyl group with 16 carbon atoms.

[0181] Performance Evaluation

[0182] Test Example 1: Evaluation of the solubility properties of different solid surfactants

[0183] The solid surfactant was prepared according to the method of Example 7. The starch type was changed to prepare different solid surfactants. The time for complete dissolution and powderization under different conditions is shown in Table 1.

[0184] Table 1 Solubility properties of solid surfactants for different starch types

[0185]

[0186] It can be seen from Table 1 that the dissolution time of different solid surfactants is roughly 6-13 hours, and the dissolution rate is relatively appropriate.

[0187] Test Example 2: Oil-water interfacial tension test of solutions after hydrolysis of different starch solids

[0188] Solid surfactants were prepared according to Example 7. The types of starch and amylase were changed to prepare different solid surfactants. The interfacial tensions with crude oil from a block of Shengli Oilfield after complete hydrolysis at different temperatures when the solid-liquid mass volume ratio was 20 were shown in Table 2.

[0189] Table 2 Oil-water interfacial tension of solutions after hydrolysis of different starch solids

[0190]

[0191] It can be seen from Table 2 that the interfacial tension of the hydrolyzed crude oil is 1.2×10 -3 -8.9×10 -3 , which proves that the active agent has a better effect.

[0192] Test Example 3

[0193] The core test experiment was carried out using the hydrolyzed solution of 9# solid starch in Experimental Example 2.

[0194] (1) The specific steps are:

[0195] 1) Saturated formation water

[0196] Place the core in the core chamber, evacuate the chamber at -0.1MPa for 4 hours, add formation water or simulated formation water, pressurize to 3-4MPa, take out the core after 1 hour, weigh it, and calculate the core pore volume and porosity based on the dry weight, wet weight and density of the core according to the following formula.

[0197]

[0198] In the formula,

[0199] V p ——core pore volume, (cm3);

[0200] m1——core wet weight, g;

[0201] m2——core dry weight, g;

[0202] ρ 水 ——Density of water, g / cm3.

[0203]

[0204] In the formula,

[0205] φ——core porosity, %

[0206] V p ——core pore volume, cm3;

[0207] V b ——Total core volume, cm3.

[0208] 2) Saturated oil

[0209] The core saturated with formation water is placed in the displacement test device, and the experimental temperature (formation temperature) is set to simulate the process of crude oil displacing formation water until no water is produced. The saturation is calculated according to the following formula.

[0210]

[0211] Where:

[0212] S o ——core saturation, %;

[0213] V0——Total volume of saturated oil, cm 3 ;

[0214] V p ——Core pore volume, cm 3 .

[0215] 3) Water flooding experiment

[0216] Water flooding is completed when the water content of the produced fluid reaches 98%. The injection pressure, cumulative oil production and cumulative liquid production are recorded at regular injection time intervals.

[0217] 4) Inject the solution hydrolyzed with the 9# solid starch in Example 2

[0218] After the water flooding was completed, 0.3 PV of the hydrolyzed solution of 9# solid starch in Example 2 was injected. The injection pressure, cumulative oil production and cumulative liquid production were recorded at regular intervals.

[0219] 5) Subsequent water flooding

[0220] Water was injected to drive oil until the water content of the produced fluid reached 98%, and the experiment was terminated. The injection pressure, cumulative oil production, and cumulative liquid production were recorded at regular intervals. The final recovery factor was calculated, and the parallel absolute error was less than 3.0%.

[0221] (2) Experimental results

[0222] After injecting the solution of solid starch hydrolysis, the recovery factors of the two cores were increased by 19.02% and 23.7%, respectively.

[0223] Table 3 Core enhanced oil recovery test results

[0224]

[0225] The above describes the embodiments of the present invention in detail. However, the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A solid surfactant, characterized in that The composition is composed of the following components in parts by mass: 100 parts of modified starch, 10-120 parts of biological enzymes, including: The structural formula of modified starch is: R2O-(CH2CH2CH2O) n -St-(OCH2CH2) m OR1, either: St-(OCH2CH2) m OR1, either: St-(OCH2CH2CH2) n OR2, where: St is a starch molecule, m is a positive integer, and 1≤m≤9; n is a positive integer, and 1≤n≤9; R1 is a straight chain alkyl or branched chain alkyl of 8 to 16 carbon atoms, and R2 is a straight chain alkyl or branched chain alkyl of 8 to 16 carbon atoms.

2. A solid surfactant as claimed in claim 1, characterized in that The biological enzyme is amylase and / or maltase.

3. A solid surfactant as claimed in claim 2, characterized in that The amylase is one or more of mesophilic amylase, thermophilic amylase, isoamylase and saccharifying enzyme.

4. The method for preparing a solid surfactant according to any one of claims 1 to 3, characterized in that: Here are the steps: (1) Grafting hydrophilic and hydrophobic groups onto starch to obtain modified starch; (2) After uniformly mixing the modified starch in the formula amount, the biological enzyme in the formula amount and an appropriate amount of water, the mixture is molded, demolded and dried to obtain a solid surfactant.

5. The method for preparing a solid surfactant according to claim 4, characterized in that: In parts by mass, step (1) comprises the following steps: (11), taking 20 to 160 parts of an organic solvent into a reaction container, then adding 36 to 40 parts of starch and 2 to 9 parts of a solid acid resin catalyst into the reaction container under stirring, and then activating at 25 to 55° C. for at least 2 hours to obtain a mixed solution; (12) adding 26 to 280 parts of fatty alcohol ether to the mixed solution obtained in step (11), heating to 50 to 130° C. and stirring while performing etherification reaction for 8 to 24 hours to obtain a reaction solution; (13) Filter the reaction solution obtained in step (12), take the filtrate, neutralize the filtrate with an alkaline substance, and perform vacuum distillation to remove most of the organic solvent to a solid sample, which is then transferred to a vacuum drying oven and dried under low temperature to obtain the modified starch.

6. The method for preparing a solid surfactant according to claim 5, characterized in that: The organic solvent in step (11) is one or more of isopropanol, dimethyl sulfoxide, acetonitrile and dimethylformamide.

7. The method for preparing a solid surfactant according to claim 6, characterized in that: The organic solvent in step (11) is a mixed solution of isopropanol and dimethyl sulfoxide, wherein: The mass ratio of isopropanol to dimethyl sulfoxide is (1-3):(1-5).

8. The method for preparing a solid surfactant according to claim 5, characterized in that: The starch in step (11) is dried before being added; The fatty alcohol ether in step (12) is added dropwise at a rate of 1 to 10 drops per second.

9. The method for preparing a solid surfactant according to claim 5, characterized in that: The starch in step (11) is one or more of corn starch, potato starch, wheat starch, cassava starch, sweet potato starch, sorghum starch and rice starch.

10. The method for preparing a solid surfactant according to claim 5, characterized in that: The solid acid resin catalyst in step (11) is a resin catalyst having a sulfonic acid group.

11. The method for preparing a solid surfactant according to claim 5, characterized in that: The fatty alcohol ether in step (12) is one or more of fatty alcohol polyoxyethylene ether and fatty alcohol polyoxypropylene ether; The molecular formula of the fatty alcohol polyoxyethylene ether is: R1O(CH2CH2O) m H, where: m is a positive integer, and 1≤m≤9, R1 is a straight chain alkyl or branched chain alkyl of 8 to 16 carbon atoms; The molecular formula of the fatty alcohol polyoxypropylene ether is: R2O(CH2CH2CH2O) n H, where: n is a positive integer, and 1≤n≤9, and R2 is a straight chain alkyl or branched chain alkyl having 8 to 16 carbon atoms.

12. The method for preparing a solid surfactant according to claim 4, characterized in that: In parts by mass, step (2) comprises the following steps: (21) Dissolve the modified starch in a formula amount into a paste with an appropriate amount of water, then add the biological enzyme in a formula amount, and stir evenly to obtain a mixture, wherein: The mass ratio of modified starch to water is 100:(5-50); (22) The mixed material obtained in step (21) is molded by a mold, and after demolding and drying, a solid surfactant is obtained.

13. The method for preparing a solid surfactant according to claim 12, characterized in that: The water added in step (21) is in liquid state and has a water temperature below 25° C.; The solid surfactant obtained in step (22) is in the shape of a rod, a block, a granule, or a honeycomb.

14. Use of the solid surfactant according to any one of claims 1 to 3 or the solid surfactant prepared by the preparation method according to any one of claims 4 to 13 as an injection and displacement agent in petroleum production.

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