CN113604208B - Nano fluid system and preparation method and application thereof - Google Patents

Abstract

The application discloses a nano fluid system and a preparation method and application thereof, wherein the nano fluid system comprises a nano material, a dispersing agent, a protective agent, a stabilizing agent and water; the nano material is prepared by reacting a mixture containing an acrylamide compound, an anionic surfactant, hydrophilic silicon dioxide and an initiator. The invention adopts the matching use of the nano material with good activity and the cheap and easily obtained chemical agent to obtain a low-tension nano fluid system, and has the advantages of small using amount, good universality on crude oil, obvious reduction of interfacial tension, simple preparation method, low cost, high efficiency and environmental protection.

Description

Nano fluid system and preparation method and application thereof

Technical Field

The application relates to a nanofluid system and a preparation method and application thereof, and belongs to the technical field of chemistry.

Background

In today of increasingly tense energy sources, the improvement of oil recovery has become a major issue of oil exploitation research, and the tertiary oil recovery research, especially the oil exploitation in a low-tension nano fluid system, is generally regarded by people. Most of crude oil after water flooding is still left in a fine capillary channel or a capillary channel with a narrow throat diameter and is in a highly dispersed state, the interfacial tension between oil and water is very high, so that the pressure difference required by the flooding is very large, and the water flooding pressure difference is far smaller than the driving pressure difference, so that the pressure difference is very difficult to increase by only increasing the pressure difference, and the characteristic of reducing the interfacial tension and increasing the number of capillaries by using a low-tension nano-fluid system is a feasible and effective method for expelling the residual oil, so that the low-tension nano-fluid system flooding technology is considered to be a technology which can greatly improve the recovery ratio, has a wide application range and has the greatest development prospect.

The mechanism for reducing the surface tension of the water-oil interface is as follows: when the semi-solid particles rich in the low-tension nanofluid system diffuse in the aqueous phase to reach the oil-water interface, ultra-low interfacial tension can be formed. If the tension is low enough, the capillary forces that trap the oil in the pore spaces forming oil droplets or residual oil slugs are weakened and the oil droplets can flow under the influence of viscous forces and gravity, thereby enhancing recovery. Among the many decisive factors affecting recovery efficiency, sweep efficiency and wash efficiency of the oil displacing agent are the most important parameters. Increasing the efficiency of oil washing is generally achieved by increasing the capillary norm, while decreasing the water-oil interfacial tension is the primary way to increase the capillary norm.

The oil-water interfacial tension is usually 20-30mN/m, and the ideal low-tension nano-fluid system can reduce the interfacial tension to 10 ^-3 -10 ^-4 mN/m, thereby greatly reducing or eliminating the capillary action of the stratum, reducing the adhesion function required by stripping the crude oil, and improving the oil washing efficiencyAnd (4) rate. By reducing the tension of the oil-water interface, the accuracy of the capillary is increased, and the oil washing efficiency and swept volume are improved.

At present, the low-tension active agent for tertiary oil recovery mostly adopts a multi-component compound system, simultaneously comprises a non-ionic surfactant and an ionic surfactant, and auxiliary agents such as alkali, alcohol and the like are added into part of the formula. And aiming at different actual oil reservoir conditions, the multi-component compound system has low applicability, and the types and specific formula proportions of non-ionic surfactants, alkali, alcohol and other medicaments need to be researched and developed again. Each re-development involves a large amount of effort.

The surfactant for tertiary oil recovery has more problems, mainly including poor activity and low oil displacement efficiency; the oil displacement system contains inorganic base, which causes damage to stratum and oil well and causes corrosion to equipment and pipelines, and the inorganic base can seriously reduce the viscosity of the polymer, so that the use concentration of the polymer can be greatly improved to reach the required viscosity, and the comprehensive cost of oil extraction is improved; surfactants have limited ability to resist high temperatures, high salt, and hypersalinity.

At present, the low-tension active agent for tertiary oil recovery is a multi-component compound system, has poor applicability to actual oil reservoir conditions, and needs to adjust the formula of each oil field block or even each well.

Disclosure of Invention

The invention constructs the nano-fluid system on the basis of combining the problems and measures the oil-water interfacial tension of the nano-fluid system, and the result shows that the nano-fluid system with a proper structure can reduce the oil-water interfacial tension to be ultra-low under a certain proportion, shows better interfacial activity, can achieve the ultra-low interfacial tension on the test results of a plurality of oil water samples of oil fields, and has very strong universality.

According to a first aspect of the present application, there is provided a nanofluid system comprising a nanomaterial, a dispersant, a protectant, a stabilizer, and water;

the nano material is prepared by reacting a mixture containing an acrylamide compound, an anionic surfactant, hydrophilic silicon dioxide and an initiator.

Optionally, the dispersant is selected from at least one of Sodium Dodecyl Benzene Sulfonate (SDBS), sodium alpha-alkenyl sulfonate (AOS), sodium fatty alcohol polyoxyethylene ether carboxylate (AEC), Sodium Dodecyl Sulfate (SDS);

the protective agent is selected from C ₁₂ ~C ₁₆ Alkyl trimethyl ammonium halides;

the stabilizer is selected from at least one of alkylphenol polyoxyethylene (OP-10), fatty alcohol polyoxyethylene ether (AEO-9) and coconut oil fatty acid diethanolamide;

preferably, said C ₁₂ ~C ₁₆ The alkyl trimethyl ammonium halide is at least one selected from cetyl trimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, and cetyl trimethyl ammonium bromide.

Optionally, the nano-fluid system comprises 0.01-0.05 wt% of nano-materials, 0.01-0.05 wt% of dispersing agents, 0.01-0.05 wt% of protective agents, 0.01-0.05 wt% of stabilizing agents and the balance of water.

Preferably, the mass content of the protective agent is 0.01%.

Preferably, the mass content of the stabilizer is 0.01%.

Alternatively, the acrylamide-based compound is selected from acrylamide;

the anionic surfactant is selected from at least one of alpha-sodium alkenyl sulfonate, sodium oleate, dodecyl benzene sulfonic acid and secondary alkyl sodium sulfonate;

the initiator is selected from inorganic peroxide initiators;

preferably, the inorganic peroxide initiator is selected from at least one of ammonium persulfate, potassium persulfate, and sodium persulfate.

Optionally, the nanofluid system has an interfacial tension of 10 ^-6 ~10 ^-4 mN/m。

According to a second aspect of the present application, there is provided a method of preparing the above nanofluid system, the method comprising:

and stirring the materials containing the nano material, the dispersing agent, the protective agent, the stabilizing agent and the water to obtain the nano fluid system.

Optionally, the preparation method comprises: adding the nano material, the dispersing agent and the protective agent into water, stirring the mixture evenly at the stirring speed of 400-600r/min, adding the stabilizing agent, and stirring the mixture evenly at the same speed to prepare the low-tension nano fluid system.

Optionally, the stirring conditions are: the temperature is 10-40 ℃; the time is 0.5-2 h.

Optionally, the preparation method comprises:

and stirring the materials containing water, the nano material, the dispersing agent and the protective agent, and then adding the stabilizing agent to obtain the nano fluid system.

Optionally, the nanomaterial is prepared by the following method:

and reacting a mixture containing an acrylamide compound, an anionic surfactant, hydrophilic silicon dioxide and an initiator to obtain the nano material.

Optionally, the reaction conditions are: the temperature is 40-80 ℃; the time is 0.5-4 h.

Optionally, the preparation method of the nanomaterial comprises:

and (2) stirring a mixture containing water, an anionic surfactant, an acrylamide compound and hydrophilic silicon dioxide, heating to 45-50 ℃, dropwise adding a solution containing an initiator, heating to 75-80 ℃, and reacting to obtain the nano material.

Optionally, in the solution containing the initiator, the mass content of the initiator is 0.3-0.8%.

Optionally, the mass ratio of the acrylamide compound, the anionic surfactant, the hydrophilic silica and the initiator is 1-5: 1-15: 0.1-1: 0.01 to 1.

According to a final aspect of the application, there is provided the use of at least one of the aforementioned nanofluid system, the nanofluid system prepared according to the aforementioned method, in oil recovery.

The ultra-low interfacial tension of the invention is lowThe oil-water interfacial tension can reach 10 in a short time under the condition of lower dosage of the force nano fluid system ^-4 mN/m or lower order of magnitude, it is suitable for tertiary oil recovery of different oil fields in order to improve the crude oil recovery, it can also be used for depressurization, increase injection and viscosity reduction of thick oil of the well, its system does not contain alkali, will not cause the injury to the stratum in use, it can also be applied to other trades such as cleaning agent, emulsifier, deinking agent as the chemical raw material. The raw materials are easy to obtain, the price is low, the performance is good, and the method is suitable for industrial production. The preparation method of the ultralow interfacial tension and low tension nano-fluid system disclosed by the invention is simple to operate, environment-friendly, suitable for industrial large-scale production and strong in universality.

The nano material as the main component of the nano fluid system is a nano base material (hydrophilic silicon dioxide) which is modified to have more excellent performance, the modified nano base material has larger interlayer spacing and better thermal stability, can be extracted from natural minerals as a novel active material raw material, and has good degradability and environmental protection; the price of other components such as a dispersing agent, a stabilizing agent, a protective agent and the like is low, the preparation process of a nano fluid system is simple, the using method is simple, the preparation can be completed only under the stirring condition, and the ultralow interfacial tension can be achieved under various oil reservoir conditions.

The main advantages of the nano material in the application are as follows: preparing an hydrophilic/hydrophobic chain segment modified nano material by using a surface active monomer with a long carbon chain and a hydrophobic and hydrophilic modifier on the basis of a natural mineral nano base material, wherein the modified nano flaky material has a hydrophilic-hydrophobic structure, an assembled film is formed and adsorbed on an oil-water interface, the oil-water interface is thickened, the mixing and dissolving of oil and water phases are enhanced, and the interfacial tension is reduced; meanwhile, the nano particles have higher specific surface energy, and the grafted long carbon chain forms a winding structure, so that the temperature resistance and salt tolerance of the nano particles are better. The nano sheet material has an hydrophilic-hydrophobic structure, can promote oil-water two-phase mixing and dissolution, has strong universality on crude oil, and can achieve ultralow interfacial tension on actual oil reservoirs.

The beneficial effects that this application can produce include:

the invention is based on the technical index of interfacial tension, adopts the nanometer active material with good activity and cheap and easily-obtained chemical agents to be matched to obtain a low-tension nanometer fluid system, and has the advantages of less usage amount, good universality on crude oil, obvious reduction of interfacial tension, simple preparation method, low cost, high efficiency and environmental protection.

Detailed Description

The present application will be described in detail with reference to examples, but the present application is not limited to these examples.

The raw materials in the examples of the present application were all purchased commercially, unless otherwise specified.

The preparation method of the nanomaterial used in the examples of the present application and comparative example 2 was as follows:

(1) weighing 3 g of monomer alpha olefin sodium sulfonate (AOS, industrial grade, mass fraction 92%) and 2 g of monomer acrylamide (AM, monomer industrial grade), 8 g of monomer Sodium Oleate (SO) and 0.36 g of hydrophilic SiO2 into a three-neck flask, adding 106.59 g of deionized water, stirring and dissolving, introducing nitrogen for 30 min, and removing oxygen in the solution;

(2) weighing 0.05g of initiator ammonium persulfate, adding 10 g of deionized water, stirring for dissolving, introducing nitrogen for 15 min, and removing oxygen in the solution;

(3) mechanically stirring the solution in the step (1) at 250 rpm, starting heating, and setting the heating temperature to be 55 ℃;

(4) and (3) dropwise adding ammonium persulfate in the solution 2 by using a constant-pressure funnel when the temperature of the solution in the flask reaches 45 ℃, simultaneously setting the reaction temperature to 80 ℃, finishing dropping the initiator in 3-10 min, starting timing when the temperature of the reaction solution reaches 80 ℃, and finishing the reaction after reacting for 3 h.

The performance test method of the embodiment of the application comprises the following steps:

the following performance tests were performed using oilfield formation simulation formulated sample solutions.

Interfacial tension: under the condition of oil reservoir temperature, using TX-500 type rotary drop interfacial tension instrument, using oil field crude oil as oil sample, continuously measuring three times and taking average value.

Comparative example 1:

weighing the raw materials according to the proportion, adding 0.03wt% of dispersant alpha-sodium olefin sulfonate AOS and 0.02wt% of protective agent hexadecyl trimethyl ammonium chloride 1631 into oil field stratum simulation water, stirring uniformly at the stirring speed of 400-plus-600 r/min, adding 0.02wt% of stabilizer fatty alcohol polyoxyethylene ether AEO-9, and stirring uniformly at the same speed to prepare the surfactant multi-component compound system.

Under the condition of oil reservoir temperature, using TX-500 type rotary drop interfacial tension instrument, using oil field crude oil as oil sample, continuously measuring three times and taking average value.

Comparative example 2:

weighing the raw materials according to the proportion, only adding 0.07wt% of nano material into the oil field stratum simulation water, and stirring the mixture evenly at the stirring speed of 400 plus materials and 600r/min to prepare the single nano active agent.

Under the condition of oil reservoir temperature, using TX-500 type rotary drop interfacial tension instrument, using oil field crude oil as oil sample, continuously measuring three times and taking average value.

Example 1:

weighing the raw materials according to the proportion, adding 0.03wt% of nano active material, 0.02wt% of dispersing agent alpha-alkenyl sodium sulfonate AOS and 0.01wt% of protective agent hexadecyl trimethyl ammonium chloride 1631 into oil field stratum simulation water, stirring uniformly at the stirring speed of 400-600r/min, adding 0.01wt% of stabilizer fatty alcohol polyoxyethylene ether AEO-9, and stirring uniformly at the same speed to prepare the low-tension nano fluid system.

Under the condition of oil reservoir temperature, using TX-500 type rotary drop interfacial tension instrument, using oil field crude oil as oil sample, continuously measuring three times and taking average value.

Example 2:

weighing the raw materials according to the proportion, adding 0.01wt% of nano active material, 0.02wt% of dispersant alpha-sodium alkenyl sulfonate AOS and 0.01wt% of protective agent dodecyl trimethyl ammonium chloride 1231 into oil field stratum simulation water, stirring the mixture evenly at the stirring speed of 400 plus materials 600r/min, adding 0.01wt% of stabilizing agent coconut oil fatty acid diethanolamide 6501, and stirring the mixture evenly at the same speed to prepare the low-tension nano fluid system.

Under the condition of oil reservoir temperature, using TX-500 type rotary drop interfacial tension instrument, using oil field crude oil as oil sample, continuously measuring three times and taking average value.

Example 3:

weighing the raw materials according to the proportion, adding 0.02wt% of nano active material, 0.03wt% of dispersant Sodium Dodecyl Sulfate (SDS), 0.01wt% of protective agent Cetyl Trimethyl Ammonium Bromide (CTAB) into oil field stratum simulation water, stirring at the stirring speed of 400 plus materials and 600r/min until the mixture is uniform, adding 0.01wt% of stabilizer alkylphenol polyoxyethylene ether OP-10, and stirring at the same speed until the mixture is uniform, thus obtaining the low-tension nano fluid system.

Under the condition of oil reservoir temperature, using TX-500 type rotary drop interfacial tension instrument, using oil field crude oil as oil sample, continuously measuring three times and taking average value.

Example 4:

weighing the raw materials according to the proportion, adding 0.02wt% of nano active material, 0.03wt% of dispersant Sodium Dodecyl Sulfate (SDS), 0.01wt% of protective agent Cetyl Trimethyl Ammonium Bromide (CTAB) into oil field stratum simulation water, stirring uniformly at the stirring speed of 400 plus materials and 600r/min, adding 0.01wt% of stabilizer coconut oil fatty acid diethanolamide 6501, and stirring uniformly at the same speed to prepare the low-tension nano fluid system.

Under the condition of oil reservoir temperature, using TX-500 type rotary drop interfacial tension instrument, using oil field crude oil as oil sample, continuously measuring three times and taking average value.

The results of the performance tests are shown in table 1.

Table 1 results of performance testing

Sample name	Test temperature	Oil sample	Water sample	Interfacial tension, mN/m
					Comparative example 1	75	Victory-1	Victory-1 simulated water	0.5
Comparative example 1	50	Changqing crude oil	Simulation water for celebration	0.2
					Comparative example 2	50	Changqing crude oil	Simulation water for celebration	0.03
Example 1	60	Changqing crude oil	Simulation water for celebration	0.00033
					Example 1	60	Island-1	Island-1 simulated water	0.00011
Example 1	55	Island-2	Island-1 simulated water	0.00034
					Example 1	75	Victory-1	Victory-1 simulated water	0.00014
Example 1	50	Bohai sea caochi Fei Dian	Clean water	0.00054
					Example 1	50	Min 20	Clean water	0.00084
Example 1	82	Xinjiang oil field	Xinjiang simulated water	0.00014
					Example 1	62	Jiangsu oil field	Clean water	0.00074
Example 2	50	Qinhuang island	Qinhuang island	0.00019
					Example 3	60	Lone dong	Lone Dong simulated water	0.00046
Example 4	62	Biannan province	Simulated waterfront	0.00053

The experimental results show that the low-tension nano-fluid system can achieve ultra-low interfacial tension under the oil reservoir conditions of a plurality of oil fields. The interfacial tension of the surfactant multi-element complex system can reach 0.5mN/m when aiming at a victory-1 oil sample, and can only reach 0.2mN/m when aiming at a Changqing crude oil sample, so that the universality is poor.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims (8)

1. A nanofluidic system comprising, in a liquid phase,

in the nano fluid system, 0.01-0.05 wt% of nano material, 0.01-0.05 wt% of dispersing agent, 0.01-0.05 wt% of protective agent, 0.01-0.05 wt% of stabilizing agent and the balance of water are contained;

the dispersing agent is selected from at least one of sodium dodecyl benzene sulfonate, alpha-sodium alkenyl sulfonate, sodium fatty alcohol polyoxyethylene ether carboxylate and sodium dodecyl sulfate;

the protective agent is selected from C ₁₂ ~C ₁₆ Alkyl trimethyl ammonium halides;

the stabilizer is selected from at least one of alkylphenol ethoxylates, fatty alcohol-polyoxyethylene ether and coconut oil fatty acid diethanolamide;

the nano material is prepared by the following method:

stirring and heating a mixture containing water, an anionic surfactant, an acrylamide compound and hydrophilic silicon dioxide to 45-50 ℃, dropwise adding a solution containing an initiator, heating to 75-80 ℃, and reacting to obtain the nano material;

the mass ratio of the acrylamide compound to the anionic surfactant to the hydrophilic silicon dioxide to the initiator is 1-5: 1-15: 0.1-1: 0.01 to 1;

the acrylamide compound is selected from acrylamide;

the anionic surfactant is a mixture of sodium alpha-alkenyl sulfonate and sodium oleate;

the initiator is selected from inorganic peroxide initiators.

2. The nanofluid system according to claim 1,

said C is ₁₂ ~C ₁₆ The alkyl trimethyl ammonium halide is at least one selected from cetyl trimethyl ammonium chloride, dodecyl trimethyl ammonium chloride, and cetyl trimethyl ammonium bromide.

3. The nanofluid system according to claim 1,

the inorganic peroxide initiator is at least one of ammonium persulfate, potassium persulfate and sodium persulfate.

4. The nanofluid system according to claim 1, wherein the nanofluid system has an oil-water interfacial tension of 10 ^-4 mN/m。

5. A method for preparing a nanofluidic system according to any one of claims 1 to 4, characterized in that it comprises:

and stirring the materials containing the nano material, the dispersing agent, the protective agent, the stabilizing agent and the water to obtain the nano fluid system.

6. The method according to claim 5, wherein the stirring conditions are: the temperature is 10-40 ℃.

7. The method of manufacturing according to claim 5, comprising:

and stirring the materials containing water, the nano material, the dispersing agent and the protective agent, and then adding the stabilizing agent to obtain the nano fluid system.

8. Use of the nanofluid system according to any one of claims 1 to 4, the nanofluid system prepared according to the method of any one of claims 5 to 7 in oil recovery.