A sacrificial anti-swelling dual-purpose agent, preparation method and displacement simulation device thereof

Abstract

The present invention belongs to the technical field of oil reservoir exploitation, and specifically relates to a sacrificial anti-swelling agent, a preparation method and a displacement simulation device. The sacrificial anti-swelling agent is compounded with potassium salt and lignin nanoparticles; wherein the lignin nanoparticles: K + The molar ratio is 1:1-3. The displacement simulation device comprises a core tube, one end of which is connected to the oil displacement agent injection system and the sacrificial anti-swelling dual-purpose agent injection system, and the other end of the core tube is connected to a measuring cylinder; a zeta potential probe is arranged on the core tube; and pressure probes are arranged at both ends of the core tube. The sacrificial anti-swelling dual-purpose agent can have the functions of both sacrificial agent and anti-swelling agent, achieving a one-dose multi-purpose effect. The lignin nanoparticles used in the sacrificial anti-swelling dual-purpose agent are prepared using papermaking wastewater as raw material, and the compounded potassium salt is also inexpensive, so the sacrificial anti-swelling dual-purpose agent of the present invention achieves multiple effects at a low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of oil reservoir exploitation, and specifically relates to a sacrificial anti-swelling dual-purpose agent, a preparation method and a displacement simulation device thereof. Background Art

[0002] Clay minerals are common minerals in reservoir rocks. Injecting incompatible fluids can easily cause clay minerals to hydrate and swell, reducing the permeability of effective pores; clay particles migrate and block effective pores. Clay anti-swelling agents prevent clay hydration and swelling by adsorbing on the surface of the reservoir. Common clay anti-swelling agents include potassium salts, organic cations, etc. Potassium salts are easily embedded in the six-membered ring of silicon and oxygen, and achieve the effect of anti-swelling through adsorption. Although they are cheap and easy to obtain, they are easily desorbed from the reservoir and have weak adsorption, so they cannot prevent swelling for a long time. Organic cationic anti-swelling agents contain a large number of adsorption groups, which can bridge between clay mineral layers and particles, are not easily washed by reservoir fluids, and have a long action time, but are expensive. Even if compounded with potassium salts, it is difficult to overcome this shortcoming. Therefore, in the prior art, relatively low-priced lignin is used as an anti-swelling agent, but the adsorption amount of lignin is small and the anti-swelling effect is poor.

[0003] In addition, during the process of enhancing oil recovery and fracturing, surfactants and polymers are easily adsorbed to the reservoir, which, on the one hand, causes the loss of oil displacement agents and fracturing fluids, and on the other hand, surfactants and polymers adsorbed to the reservoir will cause wetting reversal and reduced permeability. For this reason, sacrificial agents came into being. Sacrificial agents are more likely to occupy the adsorption sites of the reservoir and reduce the adsorption amount of surfactants and polymers through competitive adsorption. Commonly used sacrificial agents include lignin sulfonates and alkali lignin, but lignin is more difficult to adsorb to the reservoir.

[0004] Patent CN104963668 and Patent CN105013390 both disclose the use of cationic surfactant hexadecyltrimethylammonium bromide (CTAB) as a sacrificial agent. Although CTAB is more easily adsorbed on the reservoir, it is expensive and cannot play the role of a sacrificial agent in a low-cost manner.

[0005] In summary, whether using organic cations as anti-swelling agents or sacrificial agents, both have the disadvantage of high cost. Although using potassium chloride as an anti-swelling agent and using lignin as a sacrificial agent are lower in cost, their effects are limited due to their low adsorption capacity. Summary of the invention

[0006] One of the purposes of the present invention is to provide a sacrificial anti-swelling agent, which can have the functions of both a sacrificial agent and an anti-swelling agent through the compounding synergy of potassium salt and lignin nanoparticles, so as to achieve a one-agent-multiple-purpose effect, thereby improving the recovery rate and protecting the reservoir. More importantly, the lignin nanoparticles used in the sacrificial anti-swelling agent are prepared using papermaking wastewater as a raw material, and the compounded potassium salt is also inexpensive, so the sacrificial anti-swelling agent of the present invention achieves multiple effects at a low cost.

[0007] The specific technical solutions are as follows:

[0008] A sacrificial anti-swelling agent, which is compounded by potassium salt and lignin nanoparticles; wherein the lignin nanoparticles: K + The molar ratio is 1:1-3. Firstly, the lignin of the lignin nanoparticles of the present invention is derived from the waste liquid recycling of papermaking wastewater, which greatly reduces the cost. At the same time, the lignin nanoparticles have a large specific surface area and a large number of adsorption groups, which can fully and effectively play its anti-swelling effect and sacrificial agent role.

[0009] Preferably, the lignin nanoparticles: K + The molar ratio is 1:3.

[0010] In the present invention, the particle size of the lignin nanoparticles in the sacrificial anti-swelling agent is 5-35nm.

[0011] Preferably, the particle size of the lignin nanoparticles is 5 nm.

[0012] In the present invention, the sacrificial anti-swelling agent is in the form of a suspension. If the sacrificial anti-swelling agent is dried and granulated into a solid granule form, the stability of the sacrificial anti-swelling agent will be affected.

[0013] The preparation method of the sacrificial anti-swelling dual-purpose agent comprises the following steps:

[0014] (1) mixing papermaking waste liquid with a lignin concentration of 0.08-0.27 mol / L with an alkaline potassium salt solution with a concentration of 0.25-0.5 mol / L at room temperature and pressure to obtain an alkali lignin potassium salt waste liquid, wherein the concentration of the alkali lignin potassium salt is 0.1-0.25 mol / L;

[0015] (2) The waste liquid of alkali lignin potassium salt is purified by membrane separation, and the purity of lignin reaches more than 95%, thereby obtaining an alkali lignin potassium salt solution;

[0016] (3) First, the obtained alkali lignin potassium salt solution is allowed to stand for 5-10 minutes to allow the lignin to dissolve better;

[0017] Then, the pH value of the static alkali lignin potassium salt solution is adjusted to 8-12 using a 0.15-0.25 mol / L alkaline potassium salt solution, and the alkali lignin potassium salt solution is diluted to 200-250 times (by volume) and stirred for 5-10 minutes; this can prevent the particle size of the nanoparticles from being too large.

[0018] The pH value of the diluted alkali lignin potassium salt solution is then adjusted to 1-5, and after ultrasonic treatment for 0.5-1h, a mixed solution of lignin nanoparticles and potassium salt is obtained, in which lignin nanoparticles and potassium salt are dispersed. + , that is, the sacrificial anti-swelling dual-purpose agent.

[0019] In the above steps, the pH is firstly adjusted by using an alkaline potassium salt solution to increase the solubility of lignin, and at the same time, K is further introduced into the dual-purpose agent. + In the next step, acid is added to adjust the pH value to acidic, which can cause the lignin to precipitate into nanoparticles. Finally, a dark brown liquid is obtained.

[0020] In the preparation method, whether the pH value is too alkaline or too acidic, it will reduce the adsorption amount of the dual-purpose agent on the reservoir surface, thereby reducing the effect of the anti-swelling agent and sacrificial agent.

[0021] The preparation method of the present invention uses papermaking waste liquid as one of the preparation raw materials, fully utilizes the large amount of lignin contained in the papermaking waste liquid, obtains lignin nanoparticles by the above method, and uses it as an anti-swelling agent and a sacrificial agent, which can reduce costs and realize the transformation of waste into treasure.

[0022] In the present invention, the alkaline potassium salt solution in step (1) and step (3) of the method for preparing the sacrificial anti-swelling dual-purpose agent is KOH or K2CO3.

[0023] In the present invention, the membrane separation in step (2) of the method for preparing the sacrificial anti-swelling dual-purpose agent adopts a CRNP0108040C filter membrane core.

[0024] In the present invention, in step (3) of the method for preparing the sacrificial anti-swelling dual-purpose agent, the pH value of the diluted solution is adjusted to 1-5 using HNO3, HCl or H2SO4.

[0025] Another object of the present invention is to provide a displacement simulation device based on the above-mentioned sacrificial anti-swelling dual-purpose agent. Traditional displacement simulation devices can only evaluate the surfactant, polymer adsorption and displacement effect through injection end pressure, oil production, or spectral and chromatographic analysis of produced fluid, but cannot measure the zeta potential of the core, and cannot adjust the ratio between lignin nanoparticles and potassium salt in the above-mentioned sacrificial anti-swelling dual-purpose agent and the amount of slug injection according to the charge carried by the reservoir. Therefore, the present invention provides a displacement simulation device based on the above-mentioned sacrificial anti-swelling dual-purpose agent.

[0026] The specific technical solutions are as follows:

[0027] A displacement simulation device based on the above-mentioned sacrificial anti-swelling agent comprises a core tube, one end of which is connected to an oil displacement agent injection system and the sacrificial anti-swelling agent injection system, and the oil displacement agent and the sacrificial anti-swelling agent are injected into the core tube through their respective displacement injection systems. The other end of the core tube is connected to a measuring cylinder, which is used to measure the production volume. A zeta potential probe is provided on the core tube; and pressure probes are provided at both ends of the core tube. The pressure probe is used to measure the displacement pressure.

[0028] In the present invention, the core tube in the displacement simulation device is 1-1.2 m long, and a zeta potential probe is set on the core tube every 0.1-0.2 m. The zeta potential probe is used to measure the charge carried by the core, thereby optimizing the injection amount of the sacrificial anti-swelling agent and the displacement agent.

[0029] In the present invention, the core tube in the displacement simulation device is 1.2 m long; a zeta potential probe is arranged on the core tube every 0.2 m.

[0030] The beneficial effects of the present invention are:

[0031] In the present invention, potassium salt and lignin nanoparticles are combined with each other to make the advantages of the two complement each other: the potassium ions in the potassium salt can not only compress the diffuse double electric layer on the surface of the reservoir and the lignin nanoparticles, but also neutralize the negative charge of the reservoir and the lignin nanoparticles, play the role of a mordant, make the lignin nanoparticles more easily adsorbed on the reservoir, occupy more reservoir adsorption sites, and better prevent the oil displacement agent from being adsorbed. At the same time, the lignin nanoparticles form a dense adsorption layer on the surface of the reservoir, and the adsorption layer prevents potassium ions from desorbing from the reservoir. The potassium ions are better adsorbed on the reservoir, and the potassium ions play a role in stabilizing and preventing clay from swelling. Through the synergistic effect of potassium ions and lignin nanoparticles, the composite solution can be used as a cheap anti-swelling sacrificial dual-purpose agent to achieve a one-dose multi-purpose effect.

[0032] (1) The present invention uses a dual-purpose agent prepared by mixing low-cost potassium salt and lignin obtained from papermaking wastewater to replace organic cationic sacrificial agent and anti-swelling agent, thereby reducing costs.

[0033] (2) In the present invention, potassium salt and lignin complement each other and promote each other's adsorption. At the same time, they play the role of anti-swelling agent and sacrificial agent, achieving the effect of one dose with multiple uses.

[0034] (3) The present invention converts lignin into nanoparticles, thereby turning papermaking waste liquid into treasure and further increasing the adsorption capacity of lignin.

[0035] The present invention also proposes a displacement simulation device, which introduces a zeta potential probe into the device, and can better observe the adsorption of potassium ions and lignin nanoparticles by measuring the core zeta potential, and obtain the charge amount of the reservoir according to the zeta potential, thereby optimizing the ratio between potassium ions and lignin nanoparticles and the injection amount of the oil displacement agent. The function of optimizing the ratio of the sacrificial anti-swelling dual-purpose agent and the displacement agent and the slug according to the adsorption amount of the sacrificial anti-swelling dual-purpose agent and the reservoir zeta potential is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the displacement simulation device based on the sacrificial anti-swelling dual-purpose agent described in the present invention.

[0037] Figure 2 It is a comparison diagram of the core zeta potential distribution of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3.

[0038] Among them, 1 is a core tube, 2 is an oil displacement agent injection system, 3 is a sacrificial anti-swelling dual-purpose agent injection system, 4 is a measuring cylinder, 5 is a zeta potential probe, and 6 is a pressure probe. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is described in detail below in conjunction with the accompanying drawings.

[0040] It should be noted that the experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents, materials and equipment described are all commercially available unless otherwise specified.

[0041] 1. Test method for anti-swelling rate: According to SY / T5971-2016 performance evaluation method of clay stabilizer for oil and gas field fracturing, acidification and water injection, the centrifugal anti-swelling rate and long-term anti-swelling performance are obtained.

[0042] 2. Testing method for the adsorption amount of the displacing agent: The adsorption rate of the displacing agent is obtained by referring to the static adsorption experiment in patent CN105013390.

[0043] Example 1

[0044] The sacrificial anti-swelling agent is prepared by compounding potassium salt and lignin nanoparticles; wherein the lignin nanoparticles: + The molar ratio of lignin to cellulose is 1:3. The particle size of the lignin nanoparticles is 5 nm.

[0045] The preparation method of the sacrificial anti-swelling dual-purpose agent comprises the following specific steps:

[0046] (1) mixing papermaking waste liquid with a lignin concentration of 0.25 mol / L with a K2CO3 solution with a concentration of 0.25 mol / L at room temperature and pressure to obtain a waste liquid of alkali lignin potassium salt, wherein the concentration of the alkali lignin potassium salt is 0.25 mol / L;

[0047] (2) Using crnp0108040c filter membrane core, the waste liquid of alkali lignin potassium salt is purified by membrane separation, and the purity of lignin reaches more than 95%, thereby obtaining an alkali lignin potassium salt solution;

[0048] (3) First, the obtained alkali lignin potassium salt solution is allowed to stand for 5 minutes;

[0049] Then, the pH value of the alkali lignin potassium salt solution after standing was adjusted to 11.44 using 0.25 mol / L K2CO3 solution, and the alkali lignin potassium salt solution was diluted to 200 times and electromagnetically stirred for 10 min;

[0050] The pH value of the diluted alkali lignin potassium salt solution was adjusted to 1.97 with 0.25 mol / L HNO3, and after ultrasonic treatment for 0.5 h, a mixed solution of lignin nanoparticles and potassium salt was obtained. + , that is, the sacrificial anti-swelling dual-purpose agent.

[0051] The displacement simulation device based on the sacrificial anti-swelling dual-purpose agent comprises a core tube 1 of 1.2 m.

[0052] One end of the core tube 1 is connected to the oil displacement agent injection system 2 and the sacrificial anti-swelling dual-purpose agent injection system 3, and a sacrificial anti-swelling dual-purpose agent segment plug 3PV and an oil displacement agent segment plug 30PV of 0.005 mol / L SDS solution are sequentially injected into the core tube 1 through the respective injection systems, with an injection rate of 30 mL / min.

[0053] The other end of the core tube 1 is connected to a measuring cylinder 4, which is used to measure the production volume.

[0054] A zeta potential probe 5 is arranged every 0.2 m on the core tube 1 to measure the zeta potential.

[0055] Pressure probes 6 are provided at both ends of the core tube 1 for measuring the displacement pressure.

[0056] Example 2

[0057] The difference from the preparation method described in Example 1 is that in the preparation method of the sacrificial anti-swelling dual-purpose agent described in this embodiment, in step (3), the pH value of the alkaline lignin potassium salt solution after standing is adjusted to 8 using 0.25 mol / L K2CO3 solution.

[0058] The rest is the same as in Example 1.

[0059] Example 3

[0060] The difference from the preparation method described in Example 1 is that in the preparation method of the sacrificial anti-swelling dual-purpose agent described in this example, in step (3), the pH value of the diluted alkali lignin potassium salt solution is adjusted to 5 using 0.25 mol / L HNO3.

[0061] The rest is the same as in Example 1.

[0062] Comparative Example 1

[0063] In this comparative example 1, a cationic surfactant CTAB with a concentration of 0.25 mol / L is used as a sacrificial agent, and the sacrificial anti-swelling dual-purpose agent slug in the displacement simulation device of Example 1 is replaced by a CTAB slug 3PV.

[0064] Comparative Example 2

[0065] Comparative Example 2 uses sodium lignin sulfonate at a concentration of 0.25 mol / L as a sacrificial agent, without adding an anti-swelling agent, and uses sodium lignin sulfonate segment plug 1PV to replace the sacrificial anti-swelling dual-purpose agent segment plug in the displacement simulation device of Example 1, and the segment plug does not contain potassium salt.

[0066] When the average value of the zeta potential at each point in the core is equal to that in Example 1, the SDS plug is injected.

[0067] Comparative Example 3

[0068] The comparative example 3 uses KNO3 with a concentration of 1.5 mol / L as an anti-swelling agent (K + The concentration is equal to that in Example 1), no sacrificial agent is added, and the sacrificial anti-swelling dual-purpose agent segment plug in the displacement simulation device of Example 1 is replaced by KNO3 segment plug 3PV.

[0069] Comparative Example 4

[0070] The difference from the preparation method described in Example 1 is that in the preparation method of the sacrificial anti-swelling dual-purpose agent described in this embodiment, in step (3), the pH value of the alkaline lignin potassium salt solution after standing is adjusted to 13 using 0.25 mol / L K2CO3 solution.

[0071] The rest is the same as in Example 1.

[0072] The performance of the reagents described in Examples 1-3 and Comparative Examples 1-4 was measured, and the results are shown in Table 1. At the same time, the displacement effect of each reagent was measured using the displacement simulation device, and the results are shown in Table 2.

[0073] Table 1 Performance indicators of each reagent

[0074]

[0075] Table 2 Displacement effect of each reagent

[0076]

[0077] From the data in Table 1 and Table 2, we can see that:

[0078] 1. From the core zeta potential distribution diagram, it can be seen that in Comparative Example 1, CTAB is used as an anti-swelling and sacrificial dual-purpose agent. The zeta potential is high in the range of 0-0.4 m from the injection end, and then rapidly decreases with the distance from the injection end, and is low in the range of 0.8-1.2 m from the injection end, indicating that organic cations such as CTAB are more rapidly and massively adsorbed near the injection well than potassium salt and lignin, and the adsorption amount is less in the far injection well area, and can only play the role of anti-swelling agent and sacrificial agent in the near injection well area, so the effect is slightly lower than that of Example 1. In addition, the cost of CTAB is much higher than that of Example 1, so the combination of potassium salt and lignin nanoparticles has great application potential in anti-swelling agent and sacrificial agent.

[0079] 2. Comparative Example 2 uses sodium lignin sulfonate as a sacrificial agent and anti-swelling agent. Its displacement adsorption capacity is 1.21 times that of Example 1, the oil recovery is 86.1% of that of Example 1, the anti-swelling rate is 71.4% of that of Example 1, and the injection end pressure is 1.64 times that of Example 1, indicating that K + Embedding the six-membered silicon-oxygen ring allows more lignin to be adsorbed in the reservoir, acting as an anti-swelling agent and sacrificial agent.

[0080] In Example 1, potassium salt and lignin are compounded to compress the diffuse double layer of the reservoir and lignin nanoparticles, and the zeta potential in the area near the injection well is slightly higher than that in Comparative Example 2; potassium salt and lignin in the area far from the injection well promote each other's adsorption, and the zeta potential is slightly lower than that in Comparative Example 1.

[0081] 3. Comparative Example 3 uses a single potassium salt KNO3 as an anti-swelling agent, and its anti-swelling rate is 79.2% of that in Example 1. The injection end pressure is 1.48 times that in Example 1, indicating that lignin nanoparticles can prevent the migration of clay particles while slowing down the K + Desorb from the reservoir.

[0082] 4. The performance of the anti-swelling agent and sacrificial agent in Comparative Example 4 is close to that in Example 1. It can be seen that the lignin is completely dissolved when the pH value reaches above 11.44. Therefore, further increasing the pH value has little effect on the formation of lignin nanoparticles.

[0083] Experimental Example 1

[0084] 1. Experimental purpose: To investigate the relationship between lignin nanoparticles and K +The influence of the molar ratio relationship on the performance of sacrificial anti-swelling dual-purpose agent.

[0085] 2. Experimental methods:

[0086] 1. Sample preparation: 1# sacrificial anti-swelling agent lignin nanoparticles: K + The molar ratio is 1:1;

[0087] 2# Sacrificial anti-swelling agent lignin nanoparticles: K + The molar ratio is 1:2;

[0088] 3# Sacrificial anti-swelling agent lignin nanoparticles: K + The molar ratio is 1:3;

[0089] 4# Sacrificial anti-swelling agent lignin nanoparticles: K + The molar ratio is 1:4;

[0090] 5# Sacrificial anti-swelling agent lignin nanoparticles: K + The molar ratio is 1:5.

[0091] 2. Test: The displacement simulation device of the present invention was used to inject the above-mentioned different sacrificial anti-swelling dual-purpose agent plugs 3PV and the oil displacement agent plug 30PV of 0.005 mol / L SDS solution into the core tube through the displacement agent injection system thereof, and the injection rate was 30 mL / min.

[0092] 3. Experimental results: as shown in Table 3.

[0093] Table 3 Lignin nanoparticles and K + Effect of molar ratio on the performance of dual-purpose agent

[0094]

[0095] It can be seen from the data in Table 3 that when the molar ratio of lignin to potassium ions is 1:3, the performance of the anti-swelling agent and sacrificial agent is the best. When the molar ratio exceeds 1:3, after the injection of the front plug, the formation diffusion double layer is compressed, and the formation has limited adsorption of potassium ions. The larger the molar ratio, the less obvious the anti-swelling effect is, and the greater the adsorption of the displacement agent. When the molar ratio is lower than 1:3, the smaller the molar ratio, the lower the adsorption of potassium ions and lignin, so the lower the anti-swelling rate, and the greater the adsorption of the displacement agent.

[0096] Experimental Example 2

[0097] 1. Experimental purpose: To investigate the effect of the particle size of lignin nanoparticles on the performance of sacrificial anti-swelling agents.

[0098] 2. Experimental methods:

[0099] 1. Sample preparation: The particle size of the lignin nanoparticles of the 1# sacrificial anti-swelling agent is 35nm;

[0100] The particle size of the lignin nanoparticles of the 2# sacrificial anti-swelling agent is 25nm;

[0101] The particle size of the lignin nanoparticles of the 3# sacrificial anti-swelling agent is 15nm;

[0102] The particle size of the lignin nanoparticles of the 4# sacrificial anti-swelling agent is 5nm;

[0103] The particle size of the lignin nanoparticles of the 5# sacrificial anti-swelling agent is 3nm.

[0104] 2. Test: The displacement simulation device of the present invention was used to inject the above-mentioned different sacrificial anti-swelling dual-purpose agent plugs 3PV and the oil displacement agent plug 30PV of 0.005 mol / L SDS solution into the core tube through the displacement agent injection system thereof, and the injection rate was 30 mL / min.

[0105] 3. Experimental results: as shown in Table 4.

[0106] Table 4 Effect of particle size of lignin nanoparticles on the performance of dual-purpose agents

[0107]

[0108] It can be seen from Table 4 that when the particle size of lignin nanoparticles is 5nm, the performance of anti-swelling agent and sacrificial agent is the best. The smaller the particle size, the larger the specific surface area and the more adsorption groups, so K + 1. Lignin nanoparticles are more easily adsorbed in the reservoir. The higher the anti-swelling rate, the smaller the adsorption amount of the displacement agent. However, when the particle size is less than 5nm, the anti-swelling rate basically no longer increases with the decrease in particle size, and the adsorption amount of the displacement agent basically no longer decreases. Considering the comprehensive consideration of economic cost and other factors, the optimal particle size of lignin nanoparticles is 5nm.

Claims

1. A sacrificial anti-swelling dual-purpose agent, characterized in that: The sacrificial anti-swelling agent is a mixed solution with a pH value of 1.97 prepared by compounding potassium salt and lignin nanoparticles; wherein the lignin nanoparticles: K + The molar ratio of is 1:3; the particle size of the lignin nanoparticles is 5 nm; The sacrificial anti-swelling dual-purpose agent is prepared by the following steps: (1) mixing papermaking waste liquid with a lignin concentration of 0.25 mol / L with a K2CO3 solution with a concentration of 0.25 mol / L at room temperature and pressure to obtain a waste liquid of alkali lignin potassium salt, wherein the concentration of the alkali lignin potassium salt is 0.25 mol / L; (2) The waste liquid of alkali lignin potassium salt is purified by membrane separation, and the purity of lignin reaches more than 95%, thereby obtaining an alkali lignin potassium salt solution; (3) First, the obtained alkali lignin potassium salt solution is allowed to stand for 5 minutes; Then, the pH value of the alkali lignin potassium salt solution after standing was adjusted to 11.44 using a 0.25 mol / L K2CO3 solution, and the alkali lignin potassium salt solution was diluted to 200 times and stirred for 10 minutes; The pH value of the diluted alkali lignin potassium salt solution was adjusted to 1.97 with 0.25 mol / L HNO3, and ultrasonically treated for 0.5 h at room temperature and pressure to obtain a mixed solution of lignin nanoparticles and potassium salt, namely the sacrificial anti-swelling dual-purpose agent.

2. The sacrificial anti-swelling dual-purpose agent according to claim 1, characterized in that: The dosage form of the dual-purpose agent is a suspension.

3. The sacrificial anti-swelling dual-purpose agent according to claim 1, characterized in that: The membrane separation in step (2) adopts a CRNP0108040C filter membrane core.

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