A zwitterionic drainage agent and its synthesis method

Abstract

The present invention belongs to the field of tertiary oil recovery technology, and in particular to a zwitterionic drainage agent and a synthesis method thereof. The synthesis method is as follows: N-(2-aminoethyl)morpholine, ethanol, and benzyl chloride are sequentially added to a four-necked flask, the pH value is adjusted with a sodium hydroxide solution, heated, kept warm, and the pH is maintained to be not less than 8; sodium chlorosulfonate is added, heated to reflux, and the pH is maintained to be not less than 8; vacuum distillation, heating to dissolve, adjusting the pH value, extraction, and liquid separation are performed; the extract is transferred to a four-necked flask, dodecyl bromide and solid potassium carbonate are added, refluxed, filtered, the filtrate is cooled, a solid is precipitated, and dried overnight to obtain a product drainage agent. The present invention has the advantages of simple synthesis process, low surface interfacial tension, low critical micelle concentration, and high drainage rate.

Description

Technical Field

[0001] The invention belongs to the technical field of tertiary oil recovery, and particularly relates to a zwitterionic drainage agent and a synthesis method thereof. Background Art

[0002] For low- and ultra-low-permeability reservoirs such as unconventional tight sandstone, large-scale hydraulic fracturing is the primary method for reservoir transformation and is currently widely used across oilfields. However, large amounts of fracturing fluid can easily form water locks in the formation due to capillary resistance, preventing it from being discharged. This damages the formation and can lead to early stage failures. Research has shown that the greater the filtration loss of injected fracturing fluid and the longer the lost fracturing fluid remains in the formation, the greater the damage to the formation. Therefore, reducing fracturing fluid filtration and accelerating and improving fracturing fluid flowback are important measures to minimize formation damage.

[0003] Drainage aids are considered one of the key chemicals for removing water locks and reducing formation damage. Adding an appropriate amount of drainage aids can effectively improve flowback efficiency, thereby achieving the goal of removing water locks.

[0004] When high-temperature fluid flows through tiny pores, it interacts with the added drainage agent to rapidly strip away cross-linked insolubles such as colloids, asphaltene, and inorganic precipitates that have long coated the rock surface and accumulated and aged. This increases the formation pores, steam circulation space, and oil flow channels, and injection pressure decreases as the macromolecules are stripped away. Simultaneously, when the oil and drainage agent collide during flow, a chemical reaction occurs, accompanied by the release of gas, which expands the mixed fluid in the reservoir, causing an increase in formation pressure and energy.

[0005] Adding drainage aids to the fracturing fluid can reduce surface tension and increase contact angle, which helps to weaken the adsorption of the reservoir, reduce pore capillary force, and promote the discharge of fracturing fluid from the dense core. It can solve the water lock and backflow problems of fracturing fluid and formation fluid in low permeability and ultra-low permeability reservoirs.

[0006] CN111518536A discloses a drainage aid for fracturing fluids, primarily composed of the following raw materials, by mass: 10-30 parts of an amide-type nonionic surfactant, 30-60 parts of a polyoxyethylene-type nonionic surfactant, 20-40 parts of an emulsifier, 60-80 parts of a fluorocarbon surfactant, 30-50 parts of a low-molecular-weight alcohol, and 20-40 parts of a heavy metal scavenger. This drainage aid has low surface and interfacial tensions, resulting in stable performance and improved flowback efficiency. It also exhibits good compatibility with other additives, minimally impacting surface and interfacial tensions when added. Furthermore, its preparation is simple and inexpensive. However, the high content of fluorocarbon surfactant in this drainage aid formulation contributes to its high cost. Furthermore, the long fluorocarbon chains of the fluorocarbon surfactants make them difficult to degrade, and prolonged use can cause environmental damage.

[0007] CN109135718A discloses a method for preparing a fracturing acidizing foaming and drainage agent, which belongs to the field of drainage agent technology. The foam-stabilizing surfactant prepared by the present invention is mainly composed of amphoteric surfactants, which have a large relative molecular weight and a larger surface area. After sacrificing part of the foaming ability, it can form a denser and more solid interface film on the solid-liquid two-phase surface, making it difficult for bubbles to break. Dodecyl sulfobetaine molecules present a higher positive charge and are easily associated with negatively charged sodium lauryl sulfate molecules. The hydrophobic force and electrostatic force between the two molecules act together to enhance the effect of compounding and make up for the lack of foaming ability of the foam-stabilizing surfactant. The fracturing acidizing foaming and drainage agent prepared by the invention is a dual-purpose agent, which avoids the trouble of compounding foaming agents and drainage agents during construction, and foams quickly, has high bubble strength, is easier to use, and reduces costs. However, sodium hydride is used in the synthesis of raw materials of the invention. The chemical reactivity of sodium hydride is very high, and it can react strongly with oxidants, causing combustion or explosion. Therefore, the large-scale production risk is very high. Summary of the Invention

[0008] The present invention addresses the shortcomings of the above-mentioned prior art and provides a zwitterionic drainage agent and a synthesis method thereof. This invention has the advantages of a simple synthesis process, low surface and interfacial tension, low critical micelle concentration, and high drainage efficiency. The surface tension is below 27.5 mN / m, the interfacial tension is below 0.04 mN / m, the critical micelle concentration (CMC) is below 80 mg / L, and the drainage efficiency is above 91%.

[0009] One of the purposes of the present invention is to disclose a zwitterionic decontamination agent, the molecular structure of which is as follows:

[0010]

[0011] Another object of the present invention is to disclose a method for synthesizing the above-mentioned zwitterionic drainage agent, the specific steps of which are as follows:

[0012] (1) Add N-(2-aminoethyl)morpholine, ethanol, and benzyl chloride to a four-necked flask in sequence, adjust the pH to 8-9 with sodium hydroxide solution, heat to 60-65°C, and keep warm for 30-60 minutes. The pH of the sodium hydroxide solution should be maintained at not less than 8.

[0013] (2) adding sodium chlorosulfonate and heating under reflux for 1-2 hours, maintaining the pH of the sodium hydroxide solution at not less than 8;

[0014] (3) distilling under reduced pressure to dryness to obtain a viscous solid, adding deionized water and heating to dissolve, adjusting the pH to 2-3 with hydrochloric acid, extracting with toluene, and separating the liquids;

[0015] (4) Transfer the toluene extract to a four-necked flask, add dodecyl bromide and solid potassium carbonate, reflux for 12-24 hours, quickly filter while hot, cool the filtrate to below 10°C, precipitate the solid, and dry it at 80-85°C overnight to obtain the product drainage agent.

[0016] Preferably, based on 1 mole of N-(2-aminoethyl)morpholine, the amounts of benzyl chloride, sodium chlorosulfonate and dodecyl bromide are 0.8-1.2, 0.8-1.2 and 1.4-2.2 mole parts respectively.

[0017] More preferably, based on 1 mole of N-(2-aminoethyl)morpholine, the amounts of benzyl chloride, sodium chlorosulfonate and dodecyl bromide are 0.9-1.1, 0.9-1.1 and 1.6-2 mole parts respectively.

[0018] Preferably, in step (1), the weight ratio of ethanol to N-(2-aminoethyl)morpholine is 10-12:1.

[0019] Preferably, in step (3), the weight ratio of deionized water to N-(2-aminoethyl)morpholine is 6-8:1.

[0020] Preferably, in step (3), the weight ratio of toluene to N-(2-aminoethyl)morpholine is 12-15:1.

[0021] Preferably, in step (4), the weight ratio of potassium carbonate to N-(2-aminoethyl)morpholine is 2-3:1.

[0022] The synthesis reaction equation of the zwitterionic drainage agent of the present invention is as follows:

[0023]

[0024]

[0025] The zwitterionic drainage agent of the present invention incorporates three hydrophobic groups and three hydrophilic groups. The hydrophobic groups are respectively two dodecyl groups and one benzyl group, while the hydrophilic groups are a common quaternary ammonium salt, a morpholine-based quaternary ammonium salt, and a sulfonic acid group, belonging to an amphoteric surfactant. The molecule contains two ring structures and has strong temperature resistance. The molecule has high surface activity, low surface and interfacial tension, a low critical micelle concentration, a large micelle aggregation number, and a strong capacity for volume expansion. It can significantly reduce oil-water interfacial tension, increase the wetting angle, reduce rock capillary resistance, forcefully remove stratum blockages, and force the oil film to peel off, with little solid adsorption capacity.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) The raw materials for synthesizing the zwitterionic decontamination agent of the present invention are widely available and inexpensive, and the preparation process is simple;

[0028] (2) The zwitterionic degassing agent of the present invention has low surface activity, with a surface tension of less than 27.5 mN / m and an interfacial tension of less than 0.04 mN / m;

[0029] (3) The zwitterionic degassing agent of the present invention has a low critical micelle concentration (CMC), reaching below 80 mg / L;

[0030] (4) The zwitterionic drainage agent of the present invention has a high drainage rate, reaching more than 91%. DETAILED DESCRIPTION

[0031] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0032] Example 1

[0033] (1) In a four-necked flask, 0.1 mol of N-(2-aminoethyl)morpholine, 130 g of ethanol, and 0.08 mol of benzyl chloride were added in sequence. The pH was adjusted to 8-9 with sodium hydroxide solution. The mixture was heated to 60°C and kept warm for 30 min. The pH of the sodium hydroxide solution was maintained at not less than 8.

[0034] (2) Add 0.08 mol of sodium chlorosulfonate and heat under reflux for 1 h, maintaining the pH of the sodium hydroxide solution at not less than 8;

[0035] (3) Distill under reduced pressure to dryness to obtain a viscous solid, add 78 g of deionized water, heat and dissolve, adjust the pH to 2-3 with hydrochloric acid, extract with 156 g of toluene, and separate the liquids;

[0036] (4) The toluene extract was transferred to a four-necked flask, 0.14 mol of dodecyl bromide and 26.3 g of solid potassium carbonate were added, refluxed for 12 h, quickly filtered while hot, the filtrate was cooled to below 10 ° C, solids were precipitated, and dried at 80 ° C overnight to obtain the product drainage agent.

[0037] Example 2

[0038] (1) In a four-necked flask, 0.1 mol of N-(2-aminoethyl)morpholine, 156 g of ethanol, and 0.12 mol of benzyl chloride were added in sequence. The pH was adjusted to 8-9 with sodium hydroxide solution. The mixture was heated to 65°C and kept warm for 60 min. The pH of the sodium hydroxide solution was maintained at not less than 8.

[0039] (2) Add 0.12 mol of sodium chlorosulfonate and heat under reflux for 2 h, maintaining the pH of the sodium hydroxide solution at not less than 8;

[0040] (3) Distill under reduced pressure to dryness to obtain a viscous solid, add 104 g of deionized water, heat and dissolve, adjust the pH to 2-3 with hydrochloric acid, extract with 195 g of toluene, and separate the liquids;

[0041] (4) The toluene extract was transferred to a four-necked flask, 0.22 mol of dodecyl bromide and 28.8 g of solid potassium carbonate were added, refluxed for 16 h, quickly filtered while hot, the filtrate was cooled to below 10 ° C, solids were precipitated, and dried at 82 ° C overnight to obtain the product drainage agent.

[0042] Example 3

[0043] (1) In a four-necked flask, 0.1 mol of N-(2-aminoethyl)morpholine, 138 g of ethanol, and 0.085 mol of benzyl chloride were added in sequence. The pH was adjusted to 8-9 with sodium hydroxide solution. The flask was heated to 62°C and kept warm for 40 minutes. The pH of the sodium hydroxide solution was maintained at not less than 8.

[0044] (2) Add 0.09 mol of sodium chlorosulfonate and heat under reflux for 1 h, maintaining the pH of the sodium hydroxide solution at not less than 8;

[0045] (3) Distill under reduced pressure to dryness to obtain a viscous solid, add 83 g of deionized water, heat and dissolve, adjust the pH to 2-3 with hydrochloric acid, extract with 177 g of toluene, and separate the liquids;

[0046] (4) The toluene extract was transferred to a four-necked flask, 0.16 mol of dodecyl bromide and 31.4 g of solid potassium carbonate were added, refluxed for 24 h, quickly filtered while hot, the filtrate was cooled to below 10 ° C, solids were precipitated, and dried at 85 ° C overnight to obtain the product drainage agent.

[0047] Example 4

[0048] (1) In a four-necked flask, 0.1 mol of N-(2-aminoethyl)morpholine, 151 g of ethanol, and 0.11 mol of benzyl chloride were added in sequence. The pH was adjusted to 8-9 with sodium hydroxide solution. The flask was heated to 61°C and kept warm for 50 min. The pH of the sodium hydroxide solution was maintained at not less than 8.

[0049] (2) Add 0.115 mol of sodium chlorosulfonate and heat under reflux for 2 h, maintaining the pH of the sodium hydroxide solution at not less than 8;

[0050] (3) Distill under reduced pressure to dryness to obtain a viscous solid, add 100 g of deionized water, heat and dissolve, adjust the pH to 2-3 with hydrochloric acid, extract with 181 g of toluene, and separate the liquids;

[0051] (4) The toluene extract was transferred to a four-necked flask, 0.2 mol of dodecyl bromide and 39 g of solid potassium carbonate were added, refluxed for 18 h, quickly filtered while hot, the filtrate was cooled to below 10 ° C, solids were precipitated, and dried at 83 ° C overnight to obtain the product drainage agent.

[0052] Example 5

[0053] (1) In a four-necked flask, 0.1 mol of N-(2-aminoethyl)morpholine, 144 g of ethanol, and 0.09 mol of benzyl chloride were added in sequence. The pH was adjusted to 8-9 with sodium hydroxide solution. The mixture was heated to 63°C and kept warm for 45 minutes. The pH of the sodium hydroxide solution was maintained at not less than 8.

[0054] (2) Add 0.098 mol of sodium chlorosulfonate and heat under reflux for 1.5 h, maintaining the pH of the sodium hydroxide solution at not less than 8;

[0055] (3) Distill under reduced pressure to dryness to obtain a viscous solid, add 91 g of deionized water and heat to dissolve, adjust the pH to 2-3 with hydrochloric acid, extract with 166 g of toluene, and separate the liquids;

[0056] (4) The toluene extract was transferred to a four-necked flask, 0.18 mol of dodecyl bromide and 37.2 g of solid potassium carbonate were added, refluxed for 15 h, quickly filtered while hot, the filtrate was cooled to below 10 ° C, solids were precipitated, and dried at 80 ° C overnight to obtain the product drainage agent.

[0057] Example 6

[0058] (1) In a four-necked flask, 0.1 mol of N-(2-aminoethyl)morpholine, 149 g of ethanol, and 0.095 mol of benzyl chloride were added in sequence. The pH was adjusted to 8-9 with sodium hydroxide solution. The flask was heated to 62°C and kept warm for 35 minutes. The pH of the sodium hydroxide solution was maintained at not less than 8.

[0059] (2) Add 0.112 mol of sodium chlorosulfonate and heat under reflux for 1.2 h, maintaining the pH of the sodium hydroxide solution at not less than 8;

[0060] (3) Distill under reduced pressure to dryness to obtain a viscous solid, add 98 g of deionized water, heat and dissolve, adjust the pH to 2-3 with hydrochloric acid, extract with 178 g of toluene, and separate the liquids;

[0061] (4) The toluene extract was transferred to a four-necked flask, 0.19 mol of dodecyl bromide and 33.3 g of solid potassium carbonate were added, refluxed for 18 h, quickly filtered while hot, the filtrate was cooled to below 10 ° C, solids were precipitated, and dried at 85 ° C overnight to obtain the product drainage agent.

[0062] Example 7

[0063] (1) In a four-necked flask, 0.1 mol of N-(2-aminoethyl)morpholine, 150 g of ethanol, and 0.1 mol of benzyl chloride were added in sequence. The pH was adjusted to 8-9 with sodium hydroxide solution. The flask was heated to 64°C and kept warm for 55 minutes. The pH of the sodium hydroxide solution was maintained at not less than 8.

[0064] (2) Add 0.1 mol of sodium chlorosulfonate and heat under reflux for 1.6 h, maintaining the pH of the sodium hydroxide solution at not less than 8;

[0065] (3) Distill under reduced pressure to dryness to obtain a viscous solid, add 95 g of deionized water, heat and dissolve, adjust the pH to 2-3 with hydrochloric acid, extract with 190 g of toluene, and separate the liquids;

[0066] (4) The toluene extract was transferred to a four-necked flask, 0.18 mol of dodecyl bromide and 35.5 g of solid potassium carbonate were added, refluxed for 21 h, quickly filtered while hot, the filtrate was cooled to below 10 ° C, solids were precipitated, and dried at 82 ° C overnight to obtain the product drainage agent.

[0067] Example 8

[0068] The surface tension and interfacial tension were measured according to the method in SY / T 5370-2018 "Surface and interfacial tension determination method". The test samples were prepared into a 200 mg / L aqueous solution. The results are shown in Table 1. The CHZJ-2 drainage agent produced by Chengdu Jianxiang Shuguan Technology Co., Ltd. was used for comparative experiments.

[0069] From Table 1 we can see that:

[0070] (1) The surface tension of the zwitterionic drainage agent of the present invention (Examples 1-7) is lower than 27.5 mN / m when the concentration is 200 mg / L, and the lowest is 27.1 mN / m; while the surface tension of the drainage agent CHZJ-2 of Chengdu Jianxiang Shuguan Technology Co., Ltd. in the comparative example is 29.6 mN / m;

[0071] (2) The interfacial tension of the zwitterionic drainage agent of the present invention (Examples 1-7) is lower than 0.04 mN / m when the concentration is 200 mg / L, and the lowest is 0.026 mN / m; while the interfacial tension of the CHZJ-2 drainage agent of the comparative example Chengdu Jianxiang Shuguan Technology Co., Ltd. is 0.38 mN / m, which is significantly higher than that of the present invention.

[0072] Example 9

[0073] The critical micelle concentration was determined according to the method in GB / T 11276-2007 "Determination of critical micelle concentration of surfactants", and the results are shown in Table 1. A comparative experiment was conducted using CHZJ-2 drainage aid produced by Chengdu Jianxiang Shuguan Technology Co., Ltd.

[0074] It can be seen from Table 1 that the critical micelle concentrations of the zwitterionic drainage agents of the present invention (Examples 1-7) are all lower than 80 mg / L, with the lowest being 50 mg / L; while the critical micelle concentration of the comparative example CHZJ-2 drainage agent of Chengdu Jianxiang Shuguan Technology Co., Ltd. is 150 mg / L, which is significantly higher than that of the present invention.

[0075] Example 10

[0076] The drainage rate was determined according to Method 1 in SY / T 5755-2016 “Performance Evaluation Method of Drainage Agents for Fracturing and Acidizing”. The results are shown in Table 1. A comparative experiment was conducted using CHZJ-2 drainage agent from Chengdu Jianxiang Shuguan Technology Co., Ltd.

[0077] Table 1 Test results of surface tension, interfacial tension, critical micelle concentration and drainage rate

[0078]

[0079]

[0080] It can be seen from Table 1 that the drainage aid rates of the zwitterionic drainage aids of the present invention (Examples 1-7) are all greater than 91%, with the highest being 93.3%; while the drainage aid rate of the comparative example CHZJ-2 drainage aid of Chengdu Jianxiang Shuguan Technology Co., Ltd. is 81.9%, which is significantly lower than that of the present invention.

[0081] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for synthesizing a zwitterionic drainage agent, characterized in that: The specific steps of the synthetic method are as follows: (1) Add N-(2-aminoethyl)morpholine, ethanol, and benzyl chloride to a four-necked flask in sequence, adjust the pH to 8-9 with sodium hydroxide solution, heat to 60-65°C, and keep warm for 30-60 minutes. The pH of the sodium hydroxide solution should be maintained at not less than 8. (2) adding sodium chlorosulfonate and heating under reflux for 1-2 hours, maintaining the pH of the sodium hydroxide solution at not less than 8; (3) distilling under reduced pressure to dryness to obtain a viscous solid, adding deionized water and heating to dissolve, adjusting the pH to 2-3 with hydrochloric acid, extracting with toluene, and separating the liquids; (4) Transfer the toluene extract to a four-necked flask, add dodecyl bromide and solid potassium carbonate, reflux for 12-24 hours, quickly filter while hot, cool the filtrate to below 10°C, precipitate the solid, and dry it at 80-85°C overnight to obtain the product drainage agent; Based on 1 mol of N-(2-aminoethyl)morpholine, the amounts of benzyl chloride, sodium chlorosulfonate, and dodecyl bromide are 0.8-1.2, 0.8-1.2, and 1.4-2.2 mol parts, respectively; The molecular structural formula of the drainage agent is as follows:

2. The method for synthesizing a zwitterionic drainage agent according to claim 1, wherein: Based on 1 mole of N-(2-aminoethyl)morpholine, the amounts of benzyl chloride, sodium chlorosulfonate and dodecyl bromide are 0.9-1.1, 0.9-1.1 and 1.6-2 mole parts respectively.

3. The method for synthesizing a zwitterionic drainage agent according to claim 1, wherein: In step (1), the weight ratio of ethanol to N-(2-aminoethyl)morpholine is 10-12:

1.

4. The method for synthesizing a zwitterionic drainage agent according to claim 1, wherein: In step (3), the weight ratio of deionized water to N-(2-aminoethyl)morpholine is 6-8:

1.

5. The method for synthesizing a zwitterionic drainage agent according to claim 1, wherein: In step (3), the weight ratio of toluene to N-(2-aminoethyl)morpholine is 12-15:

1.

6. The method for synthesizing a zwitterionic drainage agent according to claim 1, wherein: In step (4), the weight ratio of potassium carbonate to N-(2-aminoethyl)morpholine is 2-3:

1.

7. A zwitterionic drainage agent, characterized in that The molecular structural formula of the zwitterionic drainage agent is as follows:

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