Anti-calcium bio-based surfactant for oil displacement and preparation method thereof

Abstract

The invention relates to the technical field of oil displacement, in particular to an anti-calcium bio-based surfactant for oil displacement, which comprises the following components in parts by mass: 2-3 parts of nano biological particles; 4 to 6 parts of lipopeptide; 12 to 15 parts of octadecyl dimethyl hydroxypropyl sulphobetaine; 0.5 to 1 part of a coupling agent; 92 to 97 parts of deionized water; the preparation method comprises the following steps: S1, dissolving lipopeptide and octadecyl dimethyl hydroxypropyl sulfobetaine which are subjected to ultrasonic sensitization in deionized water to obtain a mixed solution; s2, mixing the nano biological particles subjected to ultrasonic activation, a coupling agent and the mixed solution to obtain a bio-based surfactant; the bio-based surfactant prepared by the invention effectively resists interference of calcium on oil displacement performance, and maintains relatively low oil-water interfacial tension, proper system viscosity and good flowability, so that the oil displacement efficiency and calcium resistance are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of oil displacement, and specifically relates to an anti-calcium bio-based surfactant for oil displacement and a preparation method thereof. Background Art

[0002] There is a relatively high interfacial tension between crude oil and formation water in the reservoir, which makes it difficult for the crude oil to be displaced from the rock pores. The bio-based surfactant can adsorb on the oil-water interface, with its hydrophilic group facing the water phase and its hydrophobic group facing the oil phase, thus greatly reducing the oil-water interfacial tension.

[0003] Due to the biodegradability of the bio-based surfactant, it will not remain in the environment for a long time like some chemically synthesized surfactants after use, causing environmental pollution. However, in some high-temperature reservoirs, the bio-based surfactant may decompose, thus losing its properties such as reducing the interfacial tension and affecting the oil displacement effect.

[0004] To solve the above problems, the present invention decides to develop a bio-based surfactant that can adapt to complex reservoir conditions. Summary of the Invention

[0005] To solve the above problems, the present invention provides an anti-calcium bio-based surfactant for oil displacement.

[0006] An anti-calcium bio-based surfactant for oil displacement, by mass, comprises the following components:

[0007] Nano-biological particles: 2 - 3 parts;

[0008] Lipopeptide: 4 - 6 parts;

[0009] Octadecyl dimethyl hydroxypropyl sulfobetaine: 12 - 15 parts;

[0010] Coupling agent: 0.5 - 1 part;

[0011] Deionized water: 92 - 97 parts.

[0012] Further, the lipopeptide is selected from any one of surfactin, fengycin or iturin.

[0013] Note: Surfactin has strong surface activity and thermal stability, fengycin has good antifungal activity and anti-coalescence stability, and iturin has the best anti-emulsification property.

[0014] Further, the coupling agent is selected from a silane coupling agent or a titanate coupling agent.

[0015] Note: The above coupling agent can protect the oil displacement surfactant from being eroded by some chemicals (such as acids, alkalis, salts, etc.) in the reservoir.

[0016] Further, the preparation method of the nano-biological particles is as follows:

[0017] The nano-metal particles are modified by femtosecond laser. The average output power of the femtosecond laser is 10 - 20 W, the laser wavelength is 1030 nm, the repetition frequency is 300 - 600 KHz, and the laser scanning speed is 3500 - 4500 μm / s. The femtosecond laser uses existing equipment. Then, the nano-metal particles modified by femtosecond laser are dissolved in ethanol at a solid-liquid ratio of 1 g:5 - 10 mL to obtain a dispersion;

[0018] The dispersion is mixed with the bacterial solution of Bacillus at a mass ratio of 1.2 - 1.5:1. The viable bacteria count in the bacterial solution of Bacillus is 10 -8 ~10 -5 cfu / mL to obtain a composite solution. The composite solution is centrifuged, washed, and vacuum freeze-dried to obtain nano-composite particles;

[0019] Then, the nano-particles are impregnated in a polyacrylamide solution at a temperature of 35 - 45 °C, a pressure of 10 - 20 MPa, and a time of 10 - 15 min. After impregnation, they are dried to obtain nano-biological particles.

[0020] Note: Femtosecond laser modification forms some tiny pits or protrusions on the surface of the nano-metal particles, increasing the specific surface area of the nano-silver particles, thus improving their adsorption capacity with Bacillus. And during the oil displacement process, it can better contact with the oil phase and water phase, playing its surface activity role. The nano-silver particles can adsorb on the surface of Bacillus, helping Bacillus disperse better in the pores of the oil reservoir. At the same time, the metabolites of Bacillus can also prevent the aggregation of nano-silver particles. The two cooperate with each other to improve the adaptability to the oil reservoir environment. During the oil displacement process, this layer of polyacrylamide can prevent the nano-biological particles from being washed away by the oil phase or water phase, and can adjust the fluidity of the nano-biological particles in the oil displacement system.

[0021] Further, the nano-metal particles are selected from one of rhenium, silver, and zinc, and the particle size is 50 - 60 nm.

[0022] Note: In the oil reservoir environment, especially in the presence of metal ions such as calcium, rhenium nanoparticles can resist chemical corrosion and chemical reactions. During the anti-calcium process, silver nanoparticles can prevent the deposition of calcium at the key interface through adsorption, and zinc nanoparticles can react with calcium to form a relatively loose zinc-calcium compound that is easily carried away by the fluid.

[0023] Furthermore, the method for preparing the bacterial liquid of Bacillus is as follows: Bacillus is placed in an inorganic salt liquid medium for activation culture. The conditions for the activation culture are pH = 7 - 9, 45 - 55°C, 105 - 115 r / min, and the activation culture is carried out for 36 - 48 h to obtain the bacterial liquid of Bacillus.

[0024] Note: Bacillus can survive and reproduce under relatively harsh reservoir environmental conditions. The Bacillus cultured under the above conditions enables Bacillus to continue to play a role after being injected into the reservoir without losing its activity due to unsuitable environment.

[0025] The preparation method of an anti-calcium bio-based surfactant for oil displacement according to any one of the above, comprises the following steps:

[0026] S1. The lipopeptide is immersed in a sensitizing solution at 30 - 40°C for ultrasonic sensitization. The sensitizing solution is composed of n-butanol and xanthan gum with a mass ratio of 2.5 - 3:0.3. The mass concentration of n-butanol is 45 - 55%, and the mass concentration of xanthan gum is 0.2 - 0.7%. Then the ultrasonically sensitized lipopeptide and octadecyl dimethyl hydroxypropyl sulfobetaine are dissolved in deionized water to obtain a mixed solution;

[0027] S2. The nano-biological particles are immersed in an activating solution at 15 - 25°C for ultrasonic activation. The activating solution is a sodium citrate solution with a mass concentration of 0.4 - 0.6%. Then the ultrasonically activated nano-biological particles, coupling agent and the mixed solution are mixed to obtain the bio-based surfactant.

[0028] Furthermore, in step S1, the ultrasonic frequency of the ultrasonic sensitization is 85 - 95 kHz, the power is 550 - 650 W, and the time is 20 - 30 min; in step S2, the ultrasonic frequency of the ultrasonic activation is 50 - 70 kHz, the power is 550 - 650 W, and the time is 10 - 15 min.

[0029] Note: Ultrasonic treatment can accelerate the interaction between the components in the sensitizing solution and the lipopeptide through cavitation effect. Ultrasonic treatment can promote the full contact between the nano-biological particles and the activating solution and accelerate the activation process of the nano-biological particles.

[0030] Compared with the existing bio-based surfactants, the beneficial effects of the present invention are:

[0031] (1) When the nano - biological particles and lipopeptides are mixed as components of the oil - displacement surfactant in the present invention, the nano - biological particles can utilize the surface activity of their nano - silver particles, the biological activity of Bacillus, and the rheological regulation ability of polyacrylamide, and act synergistically with the surface activity of lipopeptides. Lipopeptides mainly reduce the oil - water interfacial tension. The nano - biological particles can change the wettability of reservoir rocks, improve the stability and fluidity of the system. The combined action of the two can more effectively displace oil from the rock pores and improve the oil - displacement efficiency.

[0032] (2) In the process of preparing the bio - based surfactant in the present invention, first, the lipopeptides are ultrasonically sensitized in the sensitizing solution. n - butanol can regulate the arrangement and activity of lipopeptides at the oil - water interface. In the presence of calcium, n - butanol may change the conformation of lipopeptide molecules, reducing their sensitivity to calcium. The three - dimensional network structure of xanthan gum can prevent the aggregation phenomenon caused by calcium. The nano - biological particles are ultrasonically activated in the activation solution. When calcium exists in the reservoir, sodium citrate will preferentially bind to calcium ions, thereby reducing the adverse interaction between calcium ions and surfactants and nano - biological particles. Description of the Drawings

[0033] Figure 1 is the comparison chart of the interfacial tension results of Exploration 1 of the bio - based surfactant of the present invention;

[0034] Figure 2 is the comparison chart of the interfacial tension results of Exploration 2 of the bio - based surfactant of the present invention. Detailed Embodiments

[0035] To further elaborate on the methods and achieved effects adopted by the present invention, the technical solutions of the present invention will be clearly and completely described below in combination with experiments.

[0036] Example 1: An anti - calcium bio - based surfactant for oil displacement, by mass, includes the following components:

[0037] Nano - biological particles: 2.5 parts;

[0038] Surfactin: 5 parts;

[0039] Octadecyl dimethyl hydroxypropyl sulfobetaine: 13 parts;

[0040] Silane coupling agent: 0.8 part;

[0041] Deionized water: 95 parts;

[0042] The preparation method of the nano - biological particles is as follows:

[0043] Femtosecond laser modification was carried out on nano-rhenium particles with a particle size of 53 - 57 nm. The average output power of the femtosecond laser was 15 W, the laser wavelength was 1030 nm, the repetition frequency was 450 KHz, and the laser scanning speed was 4000 μm / s. Then, the nano-metal particles modified by femtosecond laser were dissolved in ethanol at a solid-liquid ratio of 1 g : 7 mL to obtain a dispersion;

[0044] The preparation method of the bacterial liquid of the Bacillus sp. was as follows: The Bacillus sp. was placed in an inorganic salt liquid medium for activation culture. The conditions for the activation culture were pH = 8, 50 °C, 110 r / min, and the activation culture was carried out for 42 h to obtain the bacterial liquid of the Bacillus sp. The formula of the inorganic salt liquid medium was: glucose 35 g / L, ammonium chloride 5 g / L, dipotassium hydrogen phosphate 5 g / L, potassium dihydrogen phosphate 4 g / L, calcium chloride 0.6 g / L, magnesium sulfate 0.1 g / L, ferrous sulfate 0.01 g / L, manganese sulfate 0.001 g / L, copper sulfate 0.001 g / L;

[0045] The dispersion was mixed with the bacterial liquid of the Bacillus sp. at a mass ratio of 1.4 : 1. The viable bacteria count in the bacterial liquid of the Bacillus sp. was 10 -6 cfu / mL to obtain a composite liquid. The composite liquid was centrifuged at 4500 rpm for 15 min, washed with deionized water, and vacuum freeze-dried at -30 °C to obtain nano-composite particles;

[0046] Then, the nano-particles were impregnated in a polyacrylamide solution at a temperature of 40 °C, a pressure of 15 MPa, and a time of 13 min. After impregnation, they were dried at -30 °C to obtain nano-bio-particles.

[0047] Example 2: The preparation method of the calcium-resistant bio-based surfactant for enhanced oil recovery in Example 1 included the following steps:

[0048] S1. The lipopeptide was immersed in a sensitizing solution at 35 °C for ultrasonic sensitization. The sensitizing solution was composed of n-butanol and xanthan gum with a mass ratio of 2.8 : 0.3. The mass concentration of sodium chloride was 3%, the mass concentration of n-butanol was 50%, and the mass concentration of xanthan gum was 0.4%. The ultrasonic frequency of the ultrasonic sensitization was 90 kHz, the power was 600 W, and the time was 25 min. Then, the lipopeptide after ultrasonic sensitization and octadecyl dimethyl hydroxypropyl sulfobetaine were dissolved in deionized water to obtain a mixed solution;

[0049] S2. The nano-bio-particles were immersed in an activation solution at 20 °C for ultrasonic activation. The activation solution was a sodium citrate solution with a mass concentration of 0.5%. The ultrasonic frequency of the ultrasonic activation was 60 kHz, the power was 600 W, and the time was 13 min. Then, the nano-bio-particles after ultrasonic activation, the coupling agent, and the mixed solution were mixed to obtain a bio-based surfactant.

[0050] Example 3: The difference between this example and Example 1 is that the bio-based surfactant, by mass fraction, comprises the following components: nano-biological particles: 2 parts; fengycin: 6 parts; octadecyl dimethyl hydroxypropyl sulfobetaine: 12 parts; silane coupling agent: 0.5 part; deionized water: 92 parts.

[0051] Example 4: The difference between this example and Example 1 is that the bio-based surfactant, by mass fraction, comprises the following components: nano-biological particles: 3 parts; iturin: 4 parts; octadecyl dimethyl hydroxypropyl sulfobetaine: 15 parts; titanate coupling agent: 1 part; deionized water: 97 parts.

[0052] Example 5: The difference between this example and Example 1 is that the average output power of the femtosecond laser is 10 W, the laser wavelength is 1030 nm, the repetition frequency is 300 KHz, and the laser scanning speed is 3500 μm / s.

[0053] Example 6: The difference between this example and Example 1 is that the average output power of the femtosecond laser is 20 W, the laser wavelength is 1030 nm, the repetition frequency is 600 KHz, and the laser scanning speed is 4500 μm / s.

[0054] Example 7: The difference between this example and Example 1 is that the nano-metal particles after femtosecond laser modification are dissolved in ethanol at a solid-liquid ratio of 1 g: 5 mL to obtain a dispersion; the dispersion is mixed with the bacterial solution of Bacillus subtilis at a mass ratio of 1.2: 1, and the viable count in the bacterial solution of Bacillus subtilis is 10 -5 cfu / mL.

[0055] Example 8: The difference between this example and Example 1 is that the nano-metal particles after femtosecond laser modification are dissolved in ethanol at a solid-liquid ratio of 1 g: 10 mL to obtain a dispersion; the dispersion is mixed with the bacterial solution of Bacillus subtilis at a mass ratio of 1.5: 1, and the viable count in the bacterial solution of Bacillus subtilis is 10 -8 cfu / mL.

[0056] Example 9: The difference between this example and Example 1 is that the impregnation temperature is 35 °C, the pressure is 10 MPa, and the time is 10 min.

[0057] Example 10: The difference between this example and Example 1 is that the impregnation temperature is 45 °C, the pressure is 20 MPa, and the time is 15 min.

[0058] Example 11: The difference between this example and Example 1 is that the nano-metal particles are nano-silver particles with a particle size of 50 - 53 nm.

[0059] Example 12: The difference between this example and Example 1 is that the nano metal particles are nano zinc particles with a particle size of 57 - 60 nm.

[0060] Example 13: The difference between this example and Example 1 is that the conditions for activation culture are pH = 7, 45 °C, 105 r / min, and the activation culture is carried out for 36 h.

[0061] Example 14: The difference between this example and Example 1 is that the conditions for activation culture are pH = 9, 55 °C, 115 r / min, and the activation culture is carried out for 48 h.

[0062] Example 15: The difference between this example and Example 2 is that lipopeptide is immersed in a sensitizing solution at 30 °C for ultrasonic sensitization. The ultrasonic frequency is 85 kHz, the power is 550 W, and the time is 20 min.

[0063] Example 16: The difference between this example and Example 2 is that lipopeptide is immersed in a sensitizing solution at 40 °C for ultrasonic sensitization. The ultrasonic frequency is 95 kHz, the power is 650 W, and the time is 30 min.

[0064] Example 17: The difference between this example and Example 2 is that the sensitizing solution is composed of n-butanol and xanthan gum with a mass ratio of 2.5:0.3. The mass concentration of n-butanol is 45%, and the mass concentration of xanthan gum is 0.7%.

[0065] Example 18: The difference between this example and Example 2 is that the sensitizing solution is composed of n-butanol and xanthan gum with a mass ratio of 3:0.3. The mass concentration of n-butanol is 55%, and the mass concentration of xanthan gum is 0.2%.

[0066] Example 19: The difference between this example and Example 2 is that the nano bio-particles are immersed in an activation solution at 15 °C for ultrasonic activation. The ultrasonic frequency is 50 kHz, the power is 550 W, and the time is 10 min.

[0067] Example 20: The difference between this example and Example 2 is that the nano bio-particles are immersed in an activation solution at 25 °C for ultrasonic activation. The ultrasonic frequency is 70 kHz, the power is 650 W, and the time is 15 min.

[0068] Example 21: The difference between this example and Example 2 is that the activation solution is a sodium citrate solution with a mass concentration of 0.4%.

[0069] Example 22: The difference between this example and Example 2 is that the activation solution is a sodium citrate solution with a mass concentration of 0.6%.

[0070] Experimental Example: The description basis of this experimental example is the recording scheme in Example 2, aiming to clarify the actual application effect of the present invention.

[0071] Use a TX-500C rotating drop interfacial tension meter to measure the oil-water interfacial tension between the surfactants prepared in each example and Zhongyuan crude oil. Test temperature: 85°C; formation water salinity 25×10 4 mg / L, calcium and magnesium ions 2000 mg / L.

[0072] 1. Explore the influence of the components of the bio-based surfactant on the interfacial tension.

[0073] The difference between Comparative Example 1 and Example 1 is that the nano metal particles are not modified by femtosecond laser;

[0074] The difference between Comparative Example 2 and Example 1 is that impregnation is not carried out after obtaining the nano composite particles;

[0075] From Figure 1 The comparison results show that Comparative Example 1 lacks femtosecond laser modification, which reduces the surface active sites of the nano metal particles, and Comparative Example 2 lacks impregnation, which reduces the fluidity of the nano biological particles. Therefore, compared with Examples 1, 3 to 14, the interfacial tension is significantly increased, weakening the oil displacement effect;

[0076] Comparing Examples 1, 3 to 14, it can be seen that if the component ratios of the nano biological particles and lipopeptides are too small or too large, the parameters of femtosecond laser modification are too small or too large, the concentration of Bacillus is too small or too large, the impregnation parameters are too small or too large, the particle size of the nano metal particles is too small or too large, and the parameters for activating and culturing Bacillus are too small or too large, the interfacial tension of the bio-based surfactant will increase. Therefore, comprehensively comparing, the parameter effect of Example 1 is relatively better.

[0077] 2. Explore the influence of the preparation of the bio-based surfactant on the interfacial tension.

[0078] The difference between Comparative Example 3 and Example 2 is that lipopeptides are not ultrasonically sensitized;

[0079] The difference between Comparative Example 4 and Example 2 is that the nano biological particles are not ultrasonically activated;

[0080] From Figure 2 The comparison results show that Comparative Example 3 lacks the ultrasonic sensitization of lipopeptides, which reduces the activity of lipopeptides at the oil-water interface, and Comparative Example 4 lacks the ultrasonic activation of nano biological particles, which reduces their stability. Therefore, compared with Examples 2, 15 to 22, the interfacial tension is significantly increased, weakening the oil displacement effect;

[0081] Comparing Comparative Example 2 and Examples 15 to 22, it can be seen that if the ultrasonic sensitization parameters are too small or too large, the proportion of n-butanol is too small or too large, the ultrasonic activation parameters are too small or too large, or the mass concentration of the activation solution is too small or too large, the interfacial tension of the bio-based surfactant will increase. Therefore, in comprehensive comparison, the parameter effect of Example 2 is relatively better.

Claims

1. A calcium-resistant bio-based surfactant for oil displacement, characterized in that: By mass, it includes the following components: Nanobioparticles: 2-3 parts; Lipopeptide: 4-6 parts; Octadecyl dimethyl hydroxypropyl sulfobetaine: 12-15 parts; Coupling agent: 0.5-1 part; Deionized water: 92-97 parts.

2. The calcium-resistant bio-based surfactant for oil displacement according to claim 1, characterized in that: The lipopeptide is selected from any one of surfactin, fengycin or iturin.

3. The calcium-resistant bio-based surfactant for oil displacement according to claim 1, characterized in that: The coupling agent is selected from a silane coupling agent or a titanate coupling agent.

4. The calcium-resistant bio-based surfactant for oil displacement according to claim 1, characterized in that: The preparation method of the nano bioparticles is as follows: The nano-metal particles are modified by femtosecond laser, the average output power of the femtosecond laser is 10-20W, the laser wavelength is 1030nm, the repetition frequency is 300-600KHz, the laser scanning speed is 3500-4500μm / s, and then the nano-metal particles modified by femtosecond laser are dissolved in ethanol at a solid-liquid ratio of 1g:5-10mL to obtain a dispersion; The dispersion is mixed with a bacterial solution of Bacillus at a mass ratio of 1.2 to 1.5:1, wherein the number of viable bacteria in the bacterial solution of Bacillus is 10 -8 ~10 -5 cfu / mL, a composite solution was obtained, and the composite solution was centrifuged, washed, and vacuum freeze-dried to obtain nanocomposite particles; Then the nanoparticles are immersed in a polyacrylamide solution at a temperature of 35-45°C, a pressure of 10-20 MPa, and a time of 10-15 minutes. After the immersion is completed, the solution is dried to obtain nanobiological particles.

5. The calcium-resistant bio-based surfactant for oil displacement according to claim 4, characterized in that: The nano metal particles are selected from one of rhenium, silver and zinc, and have a particle size of 50 to 60 nm.

6. The calcium-resistant bio-based surfactant for oil displacement according to claim 4, characterized in that: The preparation method of the bacillus bacterial liquid is as follows: placing the bacillus in an inorganic salt liquid culture medium for activation culture, wherein the activation culture conditions are pH=7-9, 45-55°C, 105-115r / min, and activation culture for 36-48 hours to obtain the bacillus bacterial liquid.

7. The method for preparing a calcium-resistant bio-based surfactant for oil displacement according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Immerse the lipopeptide in a sensitizing solution at 30-40°C for ultrasonic sensitization. The sensitizing solution is composed of n-butanol and xanthan gum in a mass ratio of 2.5-3:0.3, the mass concentration of n-butanol is 45-55%, and the mass concentration of xanthan gum is 0.2-0.7%. Then, the ultrasonically sensitized lipopeptide and octadecyl dimethyl hydroxypropyl sulfobetaine are dissolved in deionized water to obtain a mixed solution. S2. Immerse the nano-bioparticles in an activation solution at 15-25° C. for ultrasonic activation, wherein the activation solution is a sodium citrate solution with a mass concentration of 0.4-0.6%, and then mix the nano-bioparticles after ultrasonic activation, the coupling agent and the mixed solution to obtain a bio-based surfactant.

8. The method for preparing a calcium-resistant bio-based surfactant for oil displacement according to claim 7, characterized in that: In step S1, the ultrasonic frequency of the ultrasonic sensitization is 85-95kHz, the power is 550-650W, and the time is 20-30min; in step S2, the ultrasonic frequency of the ultrasonic activation is 50-70kHz, the power is 550-650W, and the time is 10-15min.

Images