Solid surfactant and its preparation method and application

Abstract

The present application relates to a kind of solid surfactant and its preparation method and application.A kind of solid surfactant, by modified starch and biological enzyme with mass parts, the structural formula of modified starch is:R2O-(CH2CH2CH2O) n -St-(OCH2CH2) m OR1, or:St-(OCH2CH2) m OR1, or:St-(OCH2CH2CH2) n OR2.The present application also discloses the preparation method of solid surfactant, as follows: (1), grafting hydrophilic hydrophobic group on starch to obtain modified starch;(2), after the formula amount of modified starch, the formula amount of biological enzyme and the appropriate amount of water are stirred uniformly, it is molded into shape, demolding, after drying, it is obtained solid surfactant.The present application also discloses the application of the above-mentioned solid surfactant, the solid surfactant prepared by the above-mentioned preparation method as injection increasing oil displacement agent in oil exploitation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oilfield water injection development, and particularly relates to a solid surfactant and a preparation method and application thereof. BACKGROUND

[0002] The water drive reservoirs of Shengli Oilfield include whole reservoirs, fault blocks and low-permeability reservoirs, which are the cornerstone of stable development of the oilfield. However, there are the following problems in the development of the onshore water drive reservoirs: the development degree of the onshore water drive reservoirs is greatly different, there are many low-efficiency units, the production capacity is low, and the cost is high, the main reasons of which are as follows: firstly, the low-efficiency unit reservoirs have strong heterogeneity, the water sweep volume is small, and the displacement is unbalanced, which leads to low water drive development degree; secondly, the formation pressure maintenance level is low, the water injection pressure is high, which leads to low production and high cost; thirdly, the oil / solid interface of the low-efficiency unit reservoirs has strong action, the adhesion work is large, there is more residual oil in the high water cut stage (>93 %), and it is difficult for the crude oil in the micro-nano pores to be stripped, so the water drive system operates inefficiently. In order to solve the above problems existing in the development of the water drive reservoirs, the currently disclosed technical routes mainly include two categories of pressure reduction and injection increasing system and oil displacement surfactant system.

[0003] The first category: pressure reduction and injection increasing system is mainly divided into two small categories. The first small category is pressure reduction and injection increasing system containing nano silicon dioxide. For example, Chinese patent CN112552893B discloses a kind of molecular film pressure reduction and injection increasing surfactant and its preparation method. A kind of molecular film pressure reduction and injection increasing surfactant, which includes tea saponin modified betaine surfactant 15-25 parts, nano silicon dioxide 35-50 parts, metal oxide powder 25-40 parts. Chinese patent application CN106085401A discloses a kind of pressure reduction and injection increasing agent for low permeability oilfield injection well and its preparation method and application. The pressure reduction and injection increasing agent is prepared from the following components by weight percentage: multifunctional surface treatment agent 2.0%-6.5%, hydrophobic nano silicon dioxide or nano polysilicon 0.75%-3.15%, pH regulator 2%-8%, and the rest is deionized water; the multifunctional surface treatment agent is composed of the following components by weight percentage: nonionic surfactant 30%-80%, anionic surfactant 2-25%, and amphoteric surfactant 10%-50%. The second small category is surfactant pressure reduction and injection increasing system. For example, Chinese patent CN111944506B discloses a kind of pressure reduction and injection increasing active agent and its preparation method. The pressure reduction and injection increasing active agent system is composed of long-chain fatty acid diethanol amide, anionic surfactant, cationic surfactant, nano material (at least one of oil-wet modified graphene oxide, montmorillonite, and silicon dioxide), auxiliary agent, and water. Chinese patent CN101538461B discloses a kind of pressure reduction and injection increasing agent for injection well and its preparation method. The pressure reduction and injection increasing agent for injection well is composed of the following components by weight percentage: lauric acid monoethanol amide: 30-42 parts; L-valine benzyl ester p-toluenesulfonate: 2.5-4.5 parts; C8-10 alkyl glucoside: 5.5-7.5 parts; sodium nitrite: 0.5-1.0 parts; vitamin A: 0.5-1 part; fluorocarbon surfactant FN-2: 0.05-0.1 part; methanol: 25-35 parts; water: 15-35 parts.

[0004] The second category is oil displacement surfactant system, such as Chinese invention patent CN106010494B provides a low permeability oil reservoir oil displacement surfactant and its preparation and product. Among them, the method comprises: taking organic solvent as reaction solvent, in the presence of alkaline catalyst, taking non-ionic surfactant and glycidyl ether compound as raw material to carry out reaction, to obtain reaction solution, the reaction solution is hydrolyzed in the presence of pH regulator, and then reacts with metal organic salt under alkaline condition to obtain the low permeability oil reservoir oil displacement surfactant; wherein, the molar ratio of non-ionic surfactant, glycidyl ether compound, metal organic salt, alkaline catalyst and pH regulator is 8:4:4:1:2. Chinese invention patent CN104371689B discloses a kind of ultra-low interfacial tension surfactant complex system and its preparation method, a kind of ultra-low interfacial tension surfactant complex system, by mass percentage, comprising 10%~33% of amphoteric surfactant, 7%~23% of non-ionic surfactant, 1%~4% of anionic surfactant, and the balance is water.

[0005] In summary, the current pressure reduction and injection system, oil displacement surfactant system is mainly nano system, conventional liquid surfactant and its composition, its use method is mainly pumped into well by pump truck or plunger pump, which has the following shortcomings: 1, operation time is long; 2, pump truck or plunger pump equipment is needed, and the operation cost is high. SUMMARY

[0006] The purpose of the present application is to provide a solid surfactant and its preparation method and application. The solid surfactant of the present application can be put into the water injection process or the bottom of the well shaft at one time, and the alkyl glycoside alcohol ether surfactant is released by slow hydrolysis in the well shaft or the injected water, which does not need continuous pumping by pump truck or plunger pump, greatly shortens the shut-in time, saves the operation time and operation cost, and saves the artificial dosing and maintenance cost of pump truck or plunger pump. The alkyl glycoside alcohol ether surfactant released after hydrolysis of the solid surfactant can reduce the oil-water interfacial tension to 1.0x10 -3 mN / m, displace residual oil, reduce capillary resistance, and achieve the purpose of pressure reduction and injection; at the same time, it can strengthen oil washing, improve microwave and, and achieve the purpose of improving recovery rate.

[0007] Technical scheme: a solid surfactant, consisting of the following components by mass fraction:

[0008] 100 parts of modified starch, 10-120 parts of biological enzyme, wherein:

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

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

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

[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 linear or branched alkyl group of 8-16 carbons, and R2 is a linear or branched alkyl group of 8-16 carbons.

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

[0014] Still further, the amylase is one or several of mesophilic amylase, thermophilic amylase, isoamylase and saccharifying enzyme.

[0015] A preparation method of the solid surfactant according to any one of the preceding embodiments, comprising the following steps:

[0016] (1) grafting hydrophilic and hydrophobic groups on starch to obtain modified starch;

[0017] (2) mixing the modified starch, the biological enzyme and water in a formula amount, and then molding, demolding and drying to obtain the solid surfactant.

[0018] Further, step (1) comprises the following steps in terms of mass fraction:

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

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

[0021] (13) filtering the reaction solution obtained in step (12), and then taking the filtrate, and then neutralizing the filtrate with alkaline substance, and then removing most of the organic solvent by distillation under reduced pressure to obtain a solid sample, and then transferring the solid sample into a vacuum drying oven, and then drying under low temperature and vacuum to obtain the modified starch.

[0022] Further, the organic solvent in step (11) is one or several of isopropyl alcohol, dimethyl sulfoxide, acetonitrile and dimethyl formamide.

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

[0024] The mass ratio of isopropyl alcohol and dimethyl sulfoxide is (1-3):(1-5).

[0025] Further, the starch in step (11) is subjected to drying treatment before being added.

[0026] Further, 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] Further, the solid acid resin catalyst in step (11) is a resin catalyst with a sulfonic acid group, specifically one of Amberlyst 15 dry catalyst, NKC-9 resin catalyst (Elysest (Shanghai) New Material Technology Co., Ltd.), or solid acid catalyst resin T-63MP (Kehaisi Co., Ltd.).

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

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

[0030] m is a positive integer, and 1≤m≤9, R1 is a linear alkyl group or a branched alkyl group with 8-16 carbons.

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

[0032] n is a positive integer, and 1≤n≤9, R2 is a linear alkyl group or a branched alkyl group with 8-16 carbons.

[0033] Further, the fatty alcohol ether in step (12) is added in a dropwise manner, and the dropwise speed is 1-10 drops per second.

[0034] Further, step (2) includes the following steps in terms of mass parts:

[0035] (21) A formula amount of modified starch is dissolved in an appropriate amount of water to form a paste, and then a formula amount of biological enzyme is added, and after stirring uniformly, a mixture is obtained, wherein:

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

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

[0038] More specifically, the water added in step (21) is in liquid state, and the water temperature is lower than 25 DEG C.

[0039] More specifically, the solid surfactant obtained in step (22) is in the shape of one of a rod, a block, a granule, and a honeycomb.

[0040] The solid surfactant of any one of the above or prepared by the preparation method of any one of the above is applied as an injection-enhancing oil displacement agent in oil exploitation.

[0041] Method for use: the solid surfactant can be directly put into a flow pipeline or into a well bottom during operation, and under the injection water temperature, the modified starch is decomposed into alcohol ether glycoside surfactant with a polymerization degree of 1-2 under the action of different biological enzymes, so as to play the roles of pressure reduction, injection enhancement, microwave improvement, and oil washing efficiency strengthening, and finally play the role of improving water flooding development effect. The method for use is simple and convenient, and does not need operation and pump injection equipment.

[0042] Beneficial effects: the solid surfactant and the preparation method and application thereof disclosed by the application have the following beneficial effects

[0043] Beneficial effects:

[0044] 1. The operation time is relatively short;

[0045] 2. The operation cost is low without the need of pump trucks or plunger pumps and other supporting equipment;

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

[0047] Figure 1 The flow chart of the preparation method of the solid surfactant disclosed by the application is shown. DETAILED DESCRIPTION

[0048] The specific embodiment of the application is described in detail as follows.

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

[0050] The preparation method of the solid surfactant is as follows:

[0051] (1) grafting hydrophilic and hydrophobic groups on starch to obtain modified starch, and hydrolyzing the modified starch to have surface interface activity, so as to play the role of injection enhancement and oil displacement;

[0052] (2) The formula amount of modified starch, formula amount of biological enzyme and appropriate amount of water are stirred uniformly, and then molded and dried to obtain the solid surfactant.

[0053] For example, the synthesis of fatty alcohol ether modified starch using amylose and polyoxyethylene ether is as follows:

[0054]

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

[0056] Example 1

[0057] A solid surfactant, by mass, consists of the following components:

[0058] 100 parts of modified starch, 60 parts of biological enzyme, wherein:

[0059] The structural formula of the modified starch is: R20-(CH2CH2CH2O) n -St-(OCH2CH2) m OR1, wherein:

[0060] St is a starch molecule, m is 4, n is 5, R1 is a linear alkyl group of 10 carbons, and R2 is a linear alkyl group of 9 carbons.

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

[0062] Further, the amylase is a mesophilic amylase. In another embodiment, the amylase is a mixture of mesophilic amylase, thermophilic amylase and saccharifying enzyme in equal mass ratio. In another embodiment, the amylase is a thermophilic 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, the specific steps are as follows:

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

[0065] (2) The formula amount of modified starch, formula amount of biological enzyme and appropriate amount of water are stirred uniformly, and then molded and dried to obtain the solid surfactant.

[0066] Further, step (1) includes the following steps, by mass:

[0067] (11), 20 parts of organic solvent were taken in a reaction vessel, then 36 parts of starch, 2 parts of solid acid resin catalyst were added into the reaction vessel under stirring, then the mixture was activated at 25 °C for 12 h to obtain a mixed solution;

[0068] (12), 26 parts of fatty alcohol ether were added into the mixed solution obtained in step (11), and the temperature was raised to 50 °C, then the etherification reaction was carried out under stirring for 24 h to obtain a reaction solution;

[0069] (13), the reaction solution obtained in step (12) was filtered, and the filtrate was taken, then the filtrate was neutralized with alkaline substance, and most of the organic solvent was removed by distillation under reduced pressure to obtain a solid sample, then the sample was transferred to a vacuum drying oven and dried under low temperature and vacuum to obtain the modified starch.

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

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

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

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

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

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

[0076] m is 4, and R1 is a straight-chain alkyl group of 10 carbons.

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

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

[0079] Further, the fatty alcohol ether in step (12) is added dropwise, and the dropwise speed is 5 drops per second.

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

[0081] (21) dissolving the modified starch in an appropriate amount of water to form a paste, then adding the biological enzyme in the formula amount, stirring uniformly to obtain a mixture, wherein:

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

[0083] (22) molding the mixture obtained in step (21) into a solid surfactant by using a mold, and then demolding and drying.

[0084] Further, the water added in step (21) is in a liquid state, and the water temperature is lower than 25°C.

[0085] Further, 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] The solid surfactant of any one of the above or prepared by the preparation method of any one of the above is used as an oil displacement agent in oil exploitation.

[0087] Example 2

[0088] The same as example 1, the only difference is that:

[0089] A solid surfactant, in terms of mass parts, is composed of the following components:

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

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

[0092] St is a starch molecule, m is 1, n is 9, R1 is a branched alkyl group of 8 carbons, and R2 is a linear alkyl group of 16 carbons.

[0093] Example 3

[0094] The same as Example 1, with the only difference being that:

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

[0096] 100 parts of modified starch, 120 parts of biological enzyme, wherein:

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

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

[0099] Example 4

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

[0101] 100 parts of modified starch, 60 parts of biological enzyme, wherein:

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

[0103] St is a starch molecule, m is 5; R1 is a linear alkyl group of 12 carbons.

[0104] Further, the biological enzyme is maltase.

[0105] A method for preparing the above-mentioned solid surfactant, the specific steps being as follows:

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

[0107] (2) uniformly stirring the formula amount of modified starch, the formula amount of biological enzyme, and an appropriate amount of water, then molding, demolding, and drying to obtain the solid surfactant.

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

[0109] (11) Take 160 parts of organic solvent in a reaction container, then add 40 parts of starch and 9 parts of solid acid resin catalyst to the reaction container under stirring, and then activate at 55°C for 2h to obtain a mixed solution;

[0110] (12) Add 280 parts of fatty alcohol ether to the mixed solution obtained in step (11), and heat to 130°C, and then carry out etherification reaction for 8h under stirring to obtain a reaction liquid;

[0111] (13) Filter the reaction liquid obtained in step (12), take the filtrate, then neutralize the filtrate with alkaline substance, distill most of the organic solvent under reduced pressure to a solid state, and then transfer it to a vacuum drying oven, and dry under low temperature and vacuum to obtain modified starch.

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

[0113] The mass ratio of isopropyl alcohol and dimethyl sulfoxide is 3:5.

[0114] Further, the starch in step (11) is subjected to drying treatment before being added.

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

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

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

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

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

[0120] Further, the adding method of the fatty alcohol ether in step (12) is dropwise adding, and the dropwise adding speed is 1 drop per second.

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

[0122] (21) Dissolve the modified starch of the specified amount in an appropriate amount of water to form a paste, then add the bio-enzyme of the specified amount, 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 into shape using a mold, and after demolding and drying, a solid surfactant is obtained.

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

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

[0127] The application of any of the above-mentioned solid surfactants or solid surfactants prepared by any of the above-mentioned preparation methods as oil displacement enhancers in oil extraction.

[0128] Example 5

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

[0130] A solid surfactant, comprising, by weight, the following components;

[0131] 100 parts modified starch, 10 parts bio-enzyme, of which:

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

[0133] St represents a starch molecule, m represents 1; R1 represents an 8-carbon branched alkyl group.

[0134] Example 6

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

[0136] A solid surfactant, comprising, by weight, the following components;

[0137] 100 parts modified starch, 120 parts bio-enzyme, of which:

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

[0139] St represents a starch molecule, m is 9; R1 is a branched alkyl group with 16 carbons.

[0140] Example 7

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

[0142] 100 parts of modified starch, 25 parts of biological enzyme, wherein:

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

[0144] St is a starch molecule, n is 6; R2 is a linear alkyl group of 12 carbons.

[0145] Further, the biological enzyme is amylase.

[0146] Still further, the amylase is isoamylase.

[0147] A preparation method of the solid surfactant according to any one of the preceding claims, comprising the following specific steps: (1) grafting hydrophilic and hydrophobic groups on starch to obtain modified starch;

[0148] (2) uniformly stirring the formula amount of modified starch, the formula amount of biological enzyme, and an appropriate amount of water, then molding, demolding, and drying to obtain the solid surfactant.

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

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

[0151] (12) adding 100 parts of fatty alcohol ether into the mixed solution obtained in step (11), heating to 80°C, and then performing etherification reaction for 12h under stirring to obtain a reaction solution;

[0152] (13) filtering the reaction solution obtained in step (12), taking the filtrate, then neutralizing the filtrate with alkaline substance, removing most of the organic solvent by distillation under reduced pressure to obtain a solid sample, then transferring the solid sample into a vacuum drying oven, and drying under low temperature and vacuum to obtain the modified starch.

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

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

[0155] Further, the starch in step (11) is subjected to drying treatment before being added.

[0156] Further, the starch in step (11) is cassava starch.

[0157] Further, the solid acid resin catalyst in step (11) is a resin catalyst with sulfonic acid groups, specifically solid acid catalyst resin T-63MP (produced by KOSHI CO., LTD.).

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

[0159] Still further, the molecular general formula of the fatty alcohol polyoxypropylene ether is: R2O(CH2CH2CH2O) n H, wherein:

[0160] n is 6, and R2 is a linear alkyl group of 12 carbons.

[0161] Further, the fatty alcohol ether in step (12) is added dropwise, and the dropwise speed is 10 drops per second.

[0162] Further, step (2) includes the following steps in terms of mass parts:

[0163] (21) dissolving the modified starch in an appropriate amount of water to form a paste, then adding the biological enzyme in the formula amount, stirring uniformly to obtain a mixture, wherein:

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

[0165] (22) molding the mixture obtained in step (21) into a solid surfactant by using a mold, and then demolding and drying.

[0166] Still further, the water added in step (21) is in a liquid state, and the water temperature is lower than 25°C.

[0167] Still further, the solid surfactant obtained in step (22) has a shape of one of a rod, a block, a granule, and a honeycomb.

[0168] The solid surfactant of any one of the above or prepared by the preparation method of any one of the above is applied as an oil displacement agent in oil exploitation.

[0169] Example 8

[0170] The same as example 7, except that the difference is only:

[0171] A solid surfactant, consisting of the following components in terms of mass parts:

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

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

[0174] St is a starch molecule, n is 1; R2 is a straight chain alkyl group of 8 carbons.

[0175] Example 9

[0176] The same as Example 7, the only difference is that:

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

[0178] 100 parts of modified starch, 10-120 parts of biological enzyme, wherein:

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

[0180] St is a starch molecule, n is 9; R2 is a branched alkyl group of 16 carbons.

[0181] Performance evaluation

[0182] Test Example 1: Evaluation of the dissolution performance of different solid surfactants

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

[0184] Table 1 Dissolution performance of solid surfactants with different starch types

[0185]

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

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

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

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

[0190]

[0191] As can be seen from Table 2, the interfacial tension of the crude oil after hydrolysis is 1.2 x 10 -3 -8.9 x 10 -3 , which proves that the active agent has good effect.

[0192] Test Example 3

[0193] The solution after hydrolysis of the solid starch of No. 9 in Test Example 2 was used for core test experiment.

[0194] (1) The specific steps are as follows:

[0195] 1) Saturated formation water

[0196] The core was put into the core chamber, vacuumed for 4 h under the vacuum degree of -0.1 MPa, formation water or simulated formation water was added, and the pressure was increased to 3-4 MPa. After 1 h, the core was taken out, weighed, and the core pore volume and porosity were calculated according to the core dry weight, wet weight and density 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] p 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 volume of core, cm3.

[0208] 2) Saturated oil

[0209] The core saturated with formation water was put into the displacement experimental device, the experimental temperature (formation temperature) was set, the process of displacing formation water with crude oil was simulated, and the experiment was ended when there was no water. The saturation was calculated according to the following formula.

[0210]

[0211] In the formula,

[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 is injected to displace oil until the water cut of produced fluid reaches 98%, and the water flooding experiment is ended. The injection pressure, cumulative oil production and cumulative fluid production are recorded at certain intervals.

[0217] 4) Injection of the solution of hydrolyzed 9# solid starch in Example 2

[0218] After the water flooding experiment, 0.3 PV of the solution of hydrolyzed 9# solid starch in Example 2 is injected. The injection pressure, cumulative oil production and cumulative fluid production are recorded at certain intervals.

[0219] 5) Subsequent water flooding

[0220] Water is injected to displace oil until the water cut of produced fluid reaches 98%, and the experiment is ended. The injection pressure, cumulative oil production and cumulative fluid production are recorded at certain intervals. The ultimate recovery is calculated, and the parallel absolute error is less than 3.0%.

[0221] (2) Experimental results

[0222] After the injection of the solution of hydrolyzed solid starch, the two cores increase the recovery by 19.02% and 23.7%, respectively.

[0223] Table 3 Experimental results of core recovery increase

[0224]

[0225] The above detailed the embodiments of the present application. However, the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A solid surfactant, characterized by, consists of the following components by mass parts: 100 parts of modified starch, 10-120 parts of biological enzyme, wherein: The modified starch has the structural formula: R20-(CH2CH2CH20) n - St - (OCH2CH2) m OR1, or: St-(OCH2CH2) m OR1, or: St - (OCH2CH2CH2) n OR2, wherein: 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 linear alkyl group or a branched alkyl group of 8-16 carbons, and R2 is a linear alkyl group or a branched alkyl group of 8-16 carbons. The biological enzyme is amylase and / or maltase.

2. A solid surfactant according to claim 1, wherein The amylase is one or several of mesophilic amylase, high-temperature amylase, isoamylase and saccharifying enzyme.

3. The process for the preparation of solid surfactant according to any one of claims 1-2, characterized in that, The steps are as follows: (1) grafting hydrophilic and hydrophobic groups on starch to obtain modified starch; (2) stirring uniformly the formula amount of modified starch, the formula amount of biological enzyme and an appropriate amount of water, then molding, demolding and drying to obtain solid surfactant, wherein: Step (1) includes the following steps by mass parts: (11) taking 20-160 parts of organic solvent in a reaction container, then adding 36-40 parts of starch and 2-9 parts of solid acid resin catalyst in the reaction container under stirring, then activating at 25-55℃ for at least 2h to obtain a mixed solution; (12) adding 26-280 parts of fatty alcohol ether to the mixed solution obtained in step (11), heating to 50-130℃, and then carrying out etherification reaction for 8-24h under stirring to obtain a reaction solution; (13) filtering the reaction solution obtained in step (12), then neutralizing the filtrate with alkaline substance, removing most of the organic solvent by distillation under reduced pressure to obtain a solid sample, then transferring it to a vacuum drying oven, and drying under low temperature and vacuum to obtain modified starch; The solid acid resin catalyst in step (11) is a resin catalyst with sulfonic acid group; The fatty alcohol ether in step (12) is one or more of fatty alcohol polyoxyethylene ether and fatty alcohol polyoxypropylene ether; The general formula of the fatty alcohol polyoxyethylene ether is: R1O(CH2CH2O) m H, wherein: m is a positive integer, and 1≤m≤9, and R1 is a linear alkyl group or a branched alkyl group of 8-16 carbons; The general formula of the fatty alcohol polyoxypropylene ether is: R2O(CH2CH2CH2O) n H, wherein: n is a positive integer, and 1≤n≤9, and R2 is a linear alkyl group or a branched alkyl group of 8-16 carbons.

4. A process for the preparation of a solid surfactant as claimed in claim 3, wherein, The organic solvent in step (11) is one or several of isopropyl alcohol, dimethyl sulfoxide, acetonitrile and dimethylformamide.

5. A process for the preparation of a solid surfactant as claimed in claim 4, wherein, The organic solvent in step (11) is a mixed solution of isopropyl alcohol and dimethyl sulfoxide, wherein: The mass ratio of isopropyl alcohol to dimethyl sulfoxide is (1-3):(1-5).

6. A process for the preparation of a solid surfactant as claimed in claim 3, wherein, The starch in step (11) is subjected to drying treatment before being added; The fatty alcohol ether in step (12) is added in the form of dropwise addition, and the dropwise addition speed is 1-10 drops per second.

7. A process for the preparation of a solid surfactant as claimed in claim 3, wherein the process is carried out at a temperature in the range of 50°C to 70°C. The starch in step (11) is one or several of corn starch, potato starch, wheat starch, cassava starch, sweet potato starch, sorghum starch and rice starch.

8. A process for the preparation of a solid surfactant as claimed in claim 3, wherein, Step (2) includes the following steps by mass parts: (21) dissolving the formula amount of modified starch into paste with an appropriate amount of water, then adding the formula amount of biological enzyme, and stirring uniformly to obtain a mixture, wherein: The mass ratio of modified starch to water is 100:(5-50); (22) molding the mixture obtained in step (21) with a mold, demolding and drying to obtain solid surfactant.

9. A process for the preparation of a solid surfactant as claimed in claim 8, wherein, The water added in step (21) is in liquid state and has a temperature lower than 25°C; The solid surfactant obtained in step (22) has a shape of rod, block, granule or honeycomb.

10. Use of the solid surfactant according to any one of claims 1-2 or prepared by the method according to any one of claims 3-9 as an augmented oil displacement agent in oil exploitation.

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