Surfactant for oil and gas fields and preparation method thereof

Abstract

The present invention belongs to the field of oil production technology, and in particular to a surfactant for oil and gas fields and a preparation method thereof. The preparation method is as follows: laurylamine dipropylene diamine, 2-((4-formylphenyl)(methyl)amino) sodium ethanesulfonate, methanol, and a reducing agent are added to a four-necked flask equipped with a condenser, stirred and dissolved, the pH is adjusted to 3-4, heated to boiling, and refluxed to obtain an intermediate mixed solution; the above-mentioned intermediate mixed solution is transferred to a beaker, saturated salt water is added, stirred thoroughly and cooled to below 10 ° C, flocs are precipitated, allowed to settle, the upper aqueous phase is poured out, and the lower layer of aqueous flocs is centrifuged to obtain a solid; the solid obtained by centrifugation is slowly added to a sodium hydroxide solution, dissolved, and dried overnight to obtain a product surfactant. The surfactant of the present invention has the advantages of low surface tension, low interfacial tension, low critical micelle concentration, and good viscosity reduction effect.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum extraction, and in particular relates to a surfactant for oil and gas fields and a preparation method thereof. Background Art

[0002] With the rapid economic development in recent years, my country's demand for oil and its dependence on foreign countries have continued to rise, but after years of exploitation, the recovery rates of most domestic oil fields have continued to decline.

[0003] Generally speaking, oil production can be divided into three stages: 1. Primary recovery, where oil is extracted by self-flowing under the influence of internal formation pressure and is the easiest stage to extract; 2. Secondary recovery, where water or gas injection is used to increase formation pressure and typically achieves a recovery rate of around 30%; 3. To effectively utilize the remaining reserves in the formation, scholars have proposed tertiary recovery, which relies on more advanced technologies such as chemical flooding, microbial flooding, and hybrid flooding. Surfactant flooding, a chemical flooding method, is currently the fastest-growing and most promising research area. Therefore, surfactant flooding is an effective technology for developing difficult-to-extract reservoirs.

[0004] Surfactant flooding technology is a method of increasing crude oil recovery by adding surfactants to the injected water. It can effectively reduce the oil-water interfacial tension, change the wettability of the reservoir, solubilize crude oil, and reduce crude oil viscosity. It improves oil recovery efficiency by reducing the oil-water interfacial tension and increasing the oil washing capacity. It has good recovery effect, a wide range of applications, and great development potential.

[0005] CN108060094A discloses a soil composting Bacillus CGMCC No.11219. The present invention provides a soil composting Bacillus that can grow under reservoir conditions of 37-60°C using crude oil as the sole carbon source, degrading crude oil and heavy components, increasing fluidity, and thereby improving oil recovery. Furthermore, the biosurfactants, biogas, and organic acids produced by the strain interact with crude oil, further increasing its fluidity within the reservoir and improving oil recovery. This biosurfactant typically has a poor viscosity-reducing effect on crude oil, preventing the formation of a uniform oil-water emulsion. Furthermore, the oil-water interfacial tension is typically 1-10 mN / m, making it less than ideal for enhancing oil recovery.

[0006] Patent US0042911 reports a heavy oil emulsifier viscosity reducer. The cross-linked polymer, which uses polyvinyl alcohol as a backbone, can reduce the viscosity of ordinary heavy oil to about 200 mPa·s at a dosage of 0.5%. However, the dosage used in this invention is relatively large, and the viscosity reduction effect of heavy oil is less than ideal, and the effect on improving oil recovery is limited. Summary of the Invention

[0007] The present invention addresses the deficiencies of the prior art and provides a surfactant for oil and gas fields and a method for preparing the surfactant. The surfactant has the advantages of low surface tension, low interfacial tension, low critical micelle concentration, and good viscosity reduction. The critical micelle concentration can reach as low as 48 mg / L, and the viscosity reduction rate can reach 98.67%.

[0008] One of the purposes of the present invention is to disclose a surfactant for oil and gas fields, the molecular structure of the surfactant is as follows:

[0009]

[0010] Another object of the present invention is to disclose a method for preparing the above-mentioned surfactant for oil and gas fields, wherein the specific steps of the preparation method are as follows:

[0011] (1) Add laurylamine dipropylene diamine, sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, methanol, and a reducing agent to a four-necked flask equipped with a condenser, stir and dissolve, adjust the pH to 3-4 with hydrochloric acid, heat to boiling, reflux reaction to obtain an intermediate mixed solution, and cool to room temperature;

[0012] (2) The intermediate mixture was transferred to a beaker, saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, the mixture was allowed to settle, the upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid;

[0013] (3) Slowly add 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and dry it at 105-110° C. overnight to obtain the product surfactant.

[0014] In the present invention, preferably, based on 1 mole part of lauramine dipropylene diamine, the amount of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate is 3.2-4.8 mole parts; more preferably, based on 1 mole part of lauramine dipropylene diamine, the amount of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate is 3.6-4.4 mole parts.

[0015] Preferably, the weight ratio of methanol to laurylamine dipropylene diamine in step (1) is 20-30:1.

[0016] Preferably, the reducing agent in step (1) is one of sodium borohydride, sodium triacetoxyborohydride, and sodium cyanoborohydride; more preferably, the reducing agent is sodium cyanoborohydride, and the weight ratio of the reducing agent to laurylamine dipropylene diamine is 0.5-5:1.

[0017] Preferably, the reflux reaction time in step (1) is 2-4 h.

[0018] In the present invention, preferably, the weight ratio of the saturated salt water to laurylamine dipropylene diamine in step (2) is 40-60:1.

[0019] The reaction equation for synthesizing the surfactant for oil and gas fields of the present invention is as follows:

[0020]

[0021]

[0022] The surfactant for oil and gas fields of the present invention is obtained by Borch reductive amination of laurylamine dipropylene diamine and sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate. It has four sulfonic acid anion surfactant groups and six tertiary amine weakly positive surfactant groups, which are hydrophilic groups. The dodecyl group is a lipophilic group. The molecule has a large number of active groups, so the critical micelle concentration is low. The dodecyl group has a relatively long molecular chain and can therefore penetrate deep into the crude oil, easily intertwining with the crude oil and forming an O / W emulsion with the crude oil under low dynamic conditions. Under the action of the sulfonic acid and tertiary amine groups, the external phase forms a continuous water film, which can reduce flow resistance and significantly reduce crude oil viscosity, thereby improving crude oil recovery.

[0023] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0024] (1) The surfactant for oil and gas fields of the present invention has the characteristics of high surface activity and high interfacial activity. At a concentration of 300 mg / L, the surface tension (minimum) can reach 27 mN / m, and the interfacial tension (minimum) can reach 0.1×10 -3 mN / m;

[0025] (2) The surfactant for oil and gas fields of the present invention has the characteristic of low critical micelle concentration, which can reach as low as 48 mg / L;

[0026] (3) The surfactant for oil and gas fields of the present invention has a good viscosity reduction effect, and the viscosity reduction rate reaches more than 98%. DETAILED DESCRIPTION

[0027] 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.

[0028] Example 1

[0029] (1) In a four-necked flask equipped with a condenser, 20 mmol of laurylamine dipropylene diamine, 64 mmol of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, 119.8 g of methanol, and 26.9 g of sodium triacetoxyborohydride were added and dissolved. The pH was adjusted to 3-4 with hydrochloric acid, and the mixture was heated to boiling and refluxed for 2 h to obtain an intermediate mixture, which was then cooled to room temperature.

[0030] (2) The intermediate mixture was transferred to a beaker, 239.6 g of saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, which were allowed to settle. The upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid;

[0031] (3) Slowly add 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and dry at 105° C. overnight to obtain the product surfactant.

[0032] Example 2

[0033] (1) In a four-necked flask equipped with a condenser, 20 mmol of laurylamine dipropylene diamine, 96 mmol of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, 179.4 g of methanol, and 29.9 g of sodium triacetoxyborohydride were added and dissolved. The pH was adjusted to 3-4 with hydrochloric acid, and the mixture was heated to boiling and refluxed for 4 h to obtain an intermediate mixture, which was then cooled to room temperature.

[0034] (2) The intermediate mixture was transferred to a beaker, 358.8 g of saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, which were allowed to settle. The upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid;

[0035] (3) Slowly add 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and dry it at 106° C. overnight to obtain the product surfactant.

[0036] Example 3

[0037] (1) In a four-necked flask equipped with a condenser, 20 mmol of laurylamine dipropylene diamine, 72 mmol of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, 133.2 g of methanol, and 3.0 g of sodium borohydride were added and dissolved with stirring. The pH was adjusted to 3-4 with hydrochloric acid, and the mixture was heated to boiling and refluxed for 2 h to obtain an intermediate mixture, which was then cooled to room temperature.

[0038] (2) The intermediate mixture was transferred to a beaker, 266.4 g of saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, which were allowed to settle. The upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid;

[0039] (3) Slowly add 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and dry at 108° C. overnight to obtain the product surfactant.

[0040] Example 4

[0041] (1) In a four-necked flask equipped with a condenser, 20 mmol of laurylamine dipropylene diamine, 88 mmol of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, 168.8 g of methanol, and 3.44 g of sodium borohydride were added and dissolved with stirring. The pH was adjusted to 3-4 with hydrochloric acid, and the mixture was heated to boiling and refluxed for 2 h to obtain an intermediate mixture, which was then cooled to room temperature.

[0042] (2) The intermediate mixture was transferred to a beaker, 337.6 g of saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, which were allowed to settle. The upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid;

[0043] (3) Slowly add 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and dry it at 110° C. overnight to obtain the product surfactant.

[0044] Example 5

[0045] (1) In a four-necked flask equipped with a condenser, 20 mmol of laurylamine dipropylene diamine, 76 mmol of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, 144.7 g of methanol, and 5.97 g of sodium cyanoborohydride were added and dissolved with stirring. The pH was adjusted to 3-4 with hydrochloric acid, and the mixture was heated to boiling and refluxed for 2.5 h to obtain an intermediate mixture, which was then cooled to room temperature.

[0046] (2) The intermediate mixture was transferred to a beaker, 289.4 g of saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, which were allowed to settle. The upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid;

[0047] (3) Slowly add 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and dry at 105° C. overnight to obtain the product surfactant.

[0048] Example 6

[0049] (1) In a four-necked flask equipped with a condenser, 20 mmol of laurylamine dipropylene diamine, 84 mmol of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, 158.8 g of methanol, and 6.24 g of sodium cyanoborohydride were added and dissolved. The pH was adjusted to 3-4 with hydrochloric acid, and the mixture was heated to boiling and refluxed for 3 h to obtain an intermediate mixture, which was then cooled to room temperature.

[0050] (2) The intermediate mixture was transferred to a beaker, 317.6 g of saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, which were allowed to settle. The upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid;

[0051] (3) Slowly add 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and dry at 108° C. overnight to obtain the product surfactant.

[0052] Example 7

[0053] (1) In a four-necked flask equipped with a condenser, 20 mmol of laurylamine dipropylene diamine, 80 mmol of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, 166 g of methanol, and 6.55 g of sodium cyanoborohydride were added and dissolved. The pH was adjusted to 3-4 with hydrochloric acid, and the mixture was heated to boiling and refluxed for 3.5 h to obtain an intermediate mixture, which was then cooled to room temperature.

[0054] (2) The intermediate mixture was transferred to a beaker, 332 g of saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, which were allowed to settle. The upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid;

[0055] (3) Slowly add 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and dry at 105° C. overnight to obtain the product surfactant.

[0056] Example 8 Testing of surface tension and interfacial tension

[0057] The present invention was configured into a 300 mg / L aqueous solution, and the surface tension and interfacial tension were measured according to the method in SY / T 5370-2018 "Surface and interfacial tension determination method". The oil phase was crude oil produced from an oil well in an oil production plant in Shengli Oilfield.

[0058] A comparative experiment was conducted using the heavy oil viscosity reducer produced by Dongying Baiyang Petroleum Technology Co., Ltd. The results are shown in Table 1.

[0059] Example 9 Test of critical micelle concentration

[0060] The critical micelle concentration was determined according to the method in GB / T 11276-2007 “Determination of critical micelle concentration of surfactants”.

[0061] A comparative experiment was conducted using the heavy oil viscosity reducer produced by Dongying Baiyang Petroleum Technology Co., Ltd. The results are shown in Table 1.

[0062] Table 1 Test results of surface tension, interfacial tension and critical micelle concentration

[0063]

[0064] From Table 1 we can see that:

[0065] (1) The surface tension of the surfactant for oil and gas fields of the present invention (Examples 1-7) at a concentration of 300 mg / L was lower than 28 mN / m, with the lowest reaching 27 mN / m; the surface tension of the comparative experiment was 28.6 mN / m;

[0066] (2) The interfacial tension of the surfactants for oil and gas fields of the present invention (Examples 1-7) at a concentration of 300 mg / L was lower than 8.5×10 -3 mN / m, the lowest is 0.1×10 -3 mN / m; the interfacial tension of the comparative experiment is 18×10 -3 mN / m;

[0067] (3) When the surfactant for oil and gas fields of the present invention (Examples 1-7) is at a concentration of 300 mg / L, the critical micelle concentration is less than or equal to 80 mg / L, and the lowest is 48 mg / L; the critical micelle concentration of the comparative experiment is 250 mg / L.

[0068] Example 10 Evaluation of viscosity reduction

[0069] The viscosity reduction rate was tested according to the method in Q / SH1020 1519-2016 "General Technical Requirements for Viscosity Reducers for Heavy Oils". The crude oil used in the test was an oil sample from a block of Shengli Oilfield. The initial viscosity of the crude oil was 4500 mPa·s at 50°C. The produced water from this block used in the present invention was prepared into solutions of 300 mg / L and 1000 mg / L.

[0070] Table 2 Viscosity reduction test results

[0071]

[0072] From Table 1 we can see that:

[0073] (1) The viscosity reduction rate of the surfactant for oil and gas fields of the present invention (Examples 1-7) was greater than 98.2% at a concentration of 300 mg / L, with the highest reaching 98.53%. In the comparative experiment, no emulsification occurred.

[0074] (2) The viscosity reduction rates of the surfactants for oil and gas fields of the present invention (Examples 1-7) at a concentration of 1000 mg / L were all greater than 98.4%, with the highest reaching 98.67%. The viscosity reduction rate of the comparative experiment was 94%.

[0075] 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 preparing a surfactant for oil and gas fields, characterized in that: The specific steps of the preparation method are as follows: (1) Add laurylamine dipropylene diamine, sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate, methanol, and a reducing agent to a four-necked flask equipped with a condenser, stir and dissolve, adjust the pH to 3-4 with hydrochloric acid, heat to boiling, reflux reaction to obtain an intermediate mixed solution, and cool to room temperature; (2) The intermediate mixture was transferred to a beaker, saturated saline solution with a pH of 2-3 was added, the mixture was stirred thoroughly and cooled to below 10°C to precipitate flocs, the mixture was allowed to settle, the upper aqueous phase was discarded, and the lower aqueous flocs were centrifuged to obtain a solid; (3) Slowly adding 20 wt% sodium hydroxide solution to the solid obtained by centrifugation until the solid is completely dissolved, and drying at 105-110° C. overnight to obtain the product surfactant; Based on 1 mole part of laurylamine dipropylene diamine, the amount of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate is 3.2-4.8 mole parts; The reducing agent in step (1) is one of sodium borohydride, sodium triacetoxyborohydride, and sodium cyanoborohydride; The molecular structural formula of the surfactant is as follows:

2. The method for preparing a surfactant for oil and gas fields according to claim 1, characterized in that: Based on 1 mole part of laurylamine dipropylene diamine, the amount of sodium 2-((4-formylphenyl)(methyl)amino)ethanesulfonate used is 3.6-4.4 mole parts.

3. The method for preparing a surfactant for oil and gas fields according to claim 1, characterized in that: The weight ratio of methanol to laurylamine dipropylene diamine in step (1) is 20-30:

1.

4. The method for preparing a surfactant for oil and gas fields according to claim 1, wherein: The weight ratio of the reducing agent to laurylamine dipropylene diamine is 0.5-5:

1.

5. The method for preparing a surfactant for oil and gas fields according to claim 1, characterized in that: The reflux reaction time in step (1) is 2-4h.

6. The method for preparing a surfactant for oil and gas fields according to claim 1, characterized in that: The weight ratio of the saturated saline solution to laurylamine dipropylene diamine in step (2) is 40-60:

1.

7. A surfactant for oil and gas fields, characterized in that: The molecular structural formula of the surfactant is as follows:

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