CN118512938B - A method for emulsifying and reducing viscosity of heavy oil by combining magnetic field and nanoemulsion - Google Patents

Abstract

The invention relates to the technical field of emulsification viscosity reduction, and discloses a thickened oil emulsification viscosity reduction method under the combined action of a magnetic field and nano emulsion, which comprises the following steps: adding a certain amount of white oil, paraffin, oleic acid and polyether amine D230 into a beaker to form an oil phase, stirring the oil phase with a stirrer at a constant temperature of 65 ℃ for 15min, and rotating at 600-800 r/min; adding a certain amount of deionized water into another beaker, adding a certain amount of cetyltrimethylammonium bromide, and stirring at a constant temperature of 65 ℃ for 15min at a rotating speed of 600-800 r/min; dropwise adding a water phase into the oil phase by using a dropper at the constant temperature of 65 ℃ in a beaker filled with the oil phase, stirring for 30 min, and standing for 3 hours to form nano emulsion; three rows of permanent magnets with the same shape and size and magnetic field strength of 150 mT are arranged along the inner wall of a stainless steel container, quantitative thick oil is taken and placed in the container, after the constant temperature is kept at 55 ℃ for 15: 15min, quantitative nano emulsion is added, the mixture is kept at 55 ℃ for 10: 10min, stirring is carried out for 20: 20min, the rotating speed is 1300-1500 r/min, and the thick oil emulsion with the combined action of the magnetic field and the nano emulsion is obtained, wherein the viscosity reduction rate can reach 98.66%.

Description

A method for emulsifying and reducing viscosity of heavy oil by combining magnetic field and nanoemulsion

Technical Field

The invention relates to the technical field of emulsification and viscosity reduction, in particular to a method for emulsification and viscosity reduction of heavy oil by the combined action of a magnetic field and a nanoemulsion.

Background Art

As a kind of available energy, the market prospect of heavy oil is getting more and more attention. Its development and utilization are very important to alleviate the global oil resource shortage. However, the production of heavy oil is not high due to its complex component characteristics, high viscosity and poor fluidity during extraction and transportation, which affects the economic benefits. Therefore, improving the fluidity of heavy oil and further reducing energy consumption have become the focus of discussion among domestic and foreign petroleum experts. Among the many heavy oil extraction methods, the emulsification viscosity reduction method has attracted more and more attention from scientific researchers due to its advantages of green, high efficiency, non-toxic stability and low-carbon economy. It is of great significance to improve the efficiency of heavy oil viscosity reduction extraction.

Emulsification viscosity reduction technology is a viscosity reduction method that converts the friction between oil phases into friction between water phases, making the inner wall wettable, thereby greatly reducing the friction resistance of pipeline transportation. At present, this viscosity reduction technology has been widely studied and applied at home and abroad. However, there are still many technical difficulties in the preparation of emulsions with smaller particle size and stronger stability. For example, the use of a single emulsifier can only prepare emulsions with a particle size of 40~50 μm, and the storage stability of the emulsion does not exceed 1 hour. It is impossible to achieve industrial production of emulsions with nano-level particle size, and the penetration ability of the emulsion is weak, making it difficult to enter the tiny reservoir pores, resulting in poor viscosity reduction effect of heavy oil and low extraction efficiency. In the petroleum industry, the reduction of heavy oil viscosity has always been an important research topic. High crude oil viscosity will increase the difficulty and cost of oil well extraction, affecting the production efficiency and economic benefits of oil fields. Traditional viscosity reduction methods include heating, dilution, and the use of viscosity reducers, but these methods often have problems such as high energy consumption and environmental pollution.

As a new type of emulsion system, nanoemulsion has been widely used in many fields due to its unique physical and chemical properties. Nanoemulsion is a thermodynamically unstable but kinetically stable system composed of oil, water and surfactants. Its particle size is usually between 20-200 nm. Due to its unique interfacial characteristics and rheological properties, nanoemulsion provides a new and efficient method for reducing the viscosity of heavy oil.

In order to prepare an emulsion with a smaller particle size, studies have shown that the effect of a magnetic field can have a good effect. The heavy oil will form an emulsion with a smaller particle size under the emulsification of a nanoemulsion. The magnetization of the magnetic field will destroy the intermolecular forces of various hydrocarbons in the heavy oil, causing the intermolecular aggregation state to change. After the change, its colloid and asphaltene are dissolved in the heavy oil as a dispersed phase, causing the heavy oil to form droplets with a smaller particle size, thereby achieving the purpose of reducing the viscosity of the heavy oil and enhancing fluidity. Therefore, when the magnetic field and the nanoemulsion act together, a magnetization effect is generated to reduce the viscosity of the heavy oil, forming droplets with a smaller particle size, thereby achieving a better viscosity reduction effect. In summary, the present invention combines the advantages of emulsification viscosity reduction technology and magnetic field action technology, and proposes a method for emulsifying and reducing the viscosity of heavy oil in which a magnetic field and nanoemulsion act together.

Summary of the invention

The present invention aims to solve the problem of great difficulty in heavy oil extraction in China and proposes a heavy oil emulsification and viscosity reduction method by the joint action of a magnetic field and a nanoemulsion. The heavy oil emulsion is prepared by the joint action of a magnetic field and a nanoemulsion to achieve viscosity reduction of the heavy oil, thereby further improving the recovery rate of the heavy oil.

The object of the present invention is to provide a method for emulsifying and reducing the viscosity of heavy oil by the combined action of a magnetic field and a nanoemulsion, wherein the surfactant selected for the preparation of the heavy oil emulsion is a cationic surfactant cetyltrimethylammonium bromide (CTAB), and its molecular structure is shown in FIG1 .

The selected surfactant has high stability, good solubility in various solvents, no strong adsorption on the solid surface, and good use effect.

The present invention provides a method for emulsifying and reducing the viscosity of heavy oil by using a magnetic field and a nanoemulsion, and the specific steps are as follows:

(1) Prepare an oil phase containing white oil, paraffin, oleic acid, and polyetheramine D230: add 5 g white oil, 5 g paraffin, 7.106 g oleic acid, and 2.894 g polyetheramine D230 into a beaker to form the oil phase. Stir the beaker with a magnetic stirrer at a constant temperature of 65 °C, a stirring speed of 600-800 r/min, and a stirring time of 15 min.

(2) Prepare an aqueous phase containing the cationic surfactant hexadecyltrimethylammonium bromide: add 79.6 g of deionized water to another beaker, then add 0.4 g of CTAB to the aqueous phase, and stir the beaker at a constant temperature of 65 °C with a magnetic stirrer at a speed of 600-800 r/min for 15 min.

(3) The water phase and the oil phase were uniformly mixed to prepare a nanoemulsion: the beaker containing the oil phase was kept at a constant temperature of 65 °C, and the water phase was added dropwise at a rate of about ^0.1 cm3 per second using a dropper, and stirred with a magnetic stirrer for 30 min. After standing for 3 hours, a nanoemulsion was formed as shown in Figure 2;

(4) Polarizing the heavy oil through a magnetic field, mixing the nanoemulsion with the heavy oil, and stirring to form a uniform and stable heavy oil emulsion: three rows of permanent magnets are arranged along the inner wall of the stainless steel container. The shape and size of the individual permanent magnets are consistent and the magnetic field strength is the same, which is 150 mT, as shown in Figure 4. 30 ml of heavy oil is placed in a 300 ml stainless steel container, maintained at 55 °C and allowed to stand for 15 min to allow the magnetic field to fully react with the asphaltene and colloid in the heavy oil components. 70 ml of the prepared nanoemulsion is added to the stainless steel container, and the mixture is allowed to stand at a constant temperature of 55 °C for 10 min. The mixture is stirred using an HJ-5 multifunctional stirrer at a stirring speed of 1300-1500 r/min for 20 min to obtain a heavy oil emulsion with the combined action of the magnetic field and the nanoemulsion.

(5) Verify the effect of emulsification and viscosity reduction of heavy oil under the combined action of magnetic field and nanoemulsion: After operation step (4), the viscosity of the heavy oil emulsion is measured by a rotational rheometer.

Preferably according to the present invention, the nanoemulsion consists of white oil, paraffin, oleic acid, polyetheramine D230, hexadecyltrimethylammonium bromide and deionized water;

According to the preferred embodiment of the present invention, the mass fraction of hexadecyltrimethylammonium bromide in step (2) is 0.4%;

Preferably, according to the present invention, when preparing the nanoemulsion in step (3), the water phase is added to the oil phase with a dropper at a rate of about 0.1 cm ³ per second;

Preferably, according to the present invention, the nanoemulsion prepared in step (3) has a normal particle size distribution as shown in FIG3 , and about 70% of the particle sizes are distributed in the range of 2 to 12 nm;

Preferably, according to the present invention, in step (4), a permanent magnet is arranged along the inner wall of the stainless steel container;

Preferably, according to the present invention, the single permanent magnets in step (4) have the same shape and size and the same magnetic field strength, which is 150 mT;

Preferably, according to the present invention, in step (4), the mass ratio of the heavy oil to the nanoemulsion is 3:7.

The technical features and advantages of the present invention are as follows:

The invention discloses a method for emulsifying and reducing the viscosity of heavy oil by using a magnetic field and a nanoemulsion together. The raw materials are readily available, the preparation process is simple, the operation of the provided magnetic field is easy and controllable, and the heavy oil viscosity reduction effect is excellent.

The invention uniformly mixes a quantitative nanoemulsion with heavy oil to prepare a heavy oil emulsion, and realizes emulsification and viscosity reduction through the joint action of the nanoemulsion and a magnetic field. The invention makes full use of the effect of the external magnetic field to destroy the force between the hydrocarbon molecules in the heavy oil, resulting in a change in the aggregation state between the molecules, so that the colloid and asphaltene therein are dispersed and dissolved in the heavy oil, and the emulsion is better formed with the nanoemulsion. Under the joint action of the magnetic field and the nanoemulsion, the viscosity of the heavy oil can be effectively reduced, and its mining efficiency can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Purpose of the drawings: In order to more clearly illustrate the embodiments and technical solutions of the present invention, the drawings required for use in the embodiments will be simply marked and introduced below;

Figure 1 is a molecular structure diagram of hexadecyltrimethylammonium bromide;

Fig. 2 is a sample diagram of nanoemulsion;

Fig. 3 is a nanoemulsion particle size distribution histogram;

FIG4 is a diagram of a stainless steel container device with a permanent magnet mounted on the inner wall;

Figure 5 is a viscosity-temperature curve of heavy oil emulsion at 40 ℃ ~ 100 ℃ under the combined effect of magnetic field and nanoemulsion when the shear rate is 5 s ^-1 ;

Figure 6 is a viscosity-temperature curve of heavy oil, heavy oil under magnetic field, heavy oil emulsion under nanoemulsion, and heavy oil emulsion under the combined action of magnetic field and nanoemulsion at 40 ℃ ~ 100 ℃ when the shear rate is ⁵ s -1;

FIG. 7 is a comparison chart of viscosity data of heavy oil, Example 1, Example 2, and Example 3 under the conditions of a shear rate of γ =5 s ^-1 and a temperature of 50°C.

DETAILED DESCRIPTION

In order to enable those skilled in the art to better understand the technical solutions in this specification, the technical solutions in one or more embodiments of this specification will be clearly and completely described below in conjunction with the drawings in one or more embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of the specification, not all of the embodiments. Based on one or more embodiments of the specification, other embodiments obtained by ordinary technicians in this field without making creative work should all fall within the scope of protection of the embodiment solutions of this specification.

Example 1: Magnetic field acts on viscosity reduction of heavy oil

Step 1: Three rows of permanent magnets are arranged along the inner wall of the stainless steel container, as shown in Figure 4. The shape and size of the individual permanent magnets are consistent and the magnetic field strength is the same, which is 150 mT. 30 ml of heavy oil is placed in a 300 ml stainless steel container, and the temperature is maintained at 55 °C and allowed to stand for 15 min to allow the magnetic field to fully interact with the asphaltene and colloid in the heavy oil components. The heavy oil is then stirred using a HJ-5 multifunctional stirrer at a stirring speed of 1300-1500 r/min, a stirring time of 20 min, and a constant temperature of 55 °C.

Step 2: Put the magnetic field-affected thick oil into a sampling bottle to detect its viscosity.

Example 2: Nanoemulsion acts on heavy oil emulsification and viscosity reduction

Step 1: Add 5 g of white oil, 5 g of paraffin, 7.106 g of oleic acid, and 2.894 g of polyetheramine D230 to a beaker to form an oil phase. Stir the beaker with a magnetic stirrer at a constant temperature of 65 °C, a stirring speed of 600-800 r/min, and a stirring time of 15 min.

Step 2: Add 79.6 g of deionized water to another beaker, and then add 0.4 g of hexadecyltrimethylammonium bromide (CTAB) to the aqueous phase. The molecular structure of CTAB is shown in FIG1 . Stir the beaker at a constant temperature of 65°C with a magnetic stirrer at a speed of 600-800 r/min for 15 min.

Step 3: Keep the beaker containing the oil phase in step 1 at a constant temperature of 65 °C, and add the water phase dropwise at a rate of about 0.1 cm ³ per second using a dropper, stir with a magnetic stirrer for 30 min, and let stand for 3 hours to form a nanoemulsion as shown in Figure 2;

Step 4: 30 ml of heavy oil was placed in a 300 ml stainless steel container, 70 ml of the prepared nanoemulsion was added to the stainless steel container, and the mixture was allowed to stand at a constant temperature of 55 °C for 10 min, and stirred using a HJ-5 multifunctional stirrer at a stirring speed of 1300-1500 r/min for 20 min to obtain a heavy oil emulsion with nanoemulsion.

Step 5: Sample the nanoemulsion-acted heavy oil emulsion and put it into a sampling bottle to detect its viscosity.

Example 3: Magnetic field and nanoemulsion act together to emulsify and reduce viscosity of heavy oil

Step 1: Repeat step 1 of Example 2 to prepare an oil phase;

Step 2: Repeat step 2 of Example 2 to prepare an aqueous phase;

Step 3: Repeat step 3 of Example 2 to prepare a nanoemulsion;

Step 4: three rows of permanent magnets are arranged along the inner wall of the stainless steel container. The shape and size of the single permanent magnets are consistent and the magnetic field strength is the same, which is 150 mT. 30 ml of heavy oil is placed in a 300 ml stainless steel container, the temperature is kept at 55 °C and allowed to stand for 15 min, so that the magnetic field can fully react with the asphaltene and colloid in the heavy oil components. 70 ml of the prepared nanoemulsion is added to the stainless steel container, and the container is allowed to stand for 10 min at a constant temperature of 55 °C. The container is stirred with a HJ-5 multifunctional stirrer at a stirring speed of 1300-1500 r/min and a stirring time of 20 min to obtain a heavy oil emulsion with the combined action of the magnetic field and the nanoemulsion.

Step 5: The magnetic field and the nanoemulsion are used together to put the heavy oil emulsion into a sampling bottle to detect its viscosity.

Example 4: Nanoemulsion laser scattering particle size observation test

The prepared nanoemulsion droplets were tested for microscopic particle size distribution using a Brookhaven Instrument BI-200SM laser scattering instrument (particle size range: 1 nm-6 μm; molecular weight range: 500-109; molecular size range: 10-1000 nm; angle range: 15-150°; temperature control range: room temperature to 80°C; filter wheel: 532 nm; aperture wheel: 100 μm, 200 μm, 400 μm, 1 mm, 2 mm, 3 mm). The observation results are shown in Figure 3. The nanoemulsion particle size is normally distributed, with about 70% of the particle size distributed in the range of 2 to 12 nm.

Example 5: Evaluation of Viscosity Reduction Effect of Heavy Oil

The viscosity of the mixed liquid in the sampling bottle was tested. The Anton ParMCR302 rotational rheometer (coaxial cylinder system, inner domain radius ri = 13.327 mm, rotation test mold radius re = 14.450 mm, mold height I = 40.008 mm) produced by Anton Paar of Austria was used to test the viscosity of the heavy oil at a shear rate of γ = 5 s ^-1 and a temperature of 50 ℃. The viscosity of the heavy oil was 53900 mPa·s. At a shear rate of γ = 5 s ^-1 , the viscosity-temperature curve of the heavy oil emulsion under the combined action of magnetic field and nanoemulsion at 40 ℃ ~ 100 ℃ was obtained, as shown in Figure 5. The viscosity-temperature curves of heavy oil, heavy oil under the action of magnetic field, heavy oil emulsion under the action of nanoemulsion, and heavy oil emulsion under the combined action of magnetic field and nanoemulsion at 40 ℃ ~ 100 ℃ were obtained, as shown in Figure 6. The viscosity reduction effect can be evaluated by the viscosity reduction ratio R _VR , and its calculation expression is: R _VR = (( μ ₀ -μ)/ μ ₀ )×100%.

Where: R _VR is the viscosity reduction rate, %; μ ₀ is the viscosity of heavy oil at 50 °C, ; μ is the viscosity of heavy oil measured at 50 °C. .

(1) Evaluation of the effect of magnetic field on viscosity reduction of heavy oil: When the shear rate is γ = 5 s ^-1 and the temperature is 50 °C, the viscosity of heavy oil under the action of magnetic field is 40300 mPa·s. Compared with the viscosity of heavy oil at 50 °C, the viscosity is reduced by 13600 mPa·s, and the viscosity reduction rate is 25.23%;

(2) Evaluation of the viscosity reduction effect of nanoemulsion on heavy oil emulsification: When the shear rate is γ = 5 s ^-1 and the temperature is 50 ℃, the viscosity of the heavy oil emulsion treated with nanoemulsion is 1660 mPa·s. Compared with the viscosity of the heavy oil at 50 ℃, the viscosity is reduced by 52240 mPa·s, and the viscosity reduction rate is 96.92%;

(3) Evaluation of the viscosity reduction effect of the combined action of magnetic field and nanoemulsion on heavy oil emulsification: When the shear rate is γ = 5 s ^-1 and the temperature is 50 ℃, the viscosity of the heavy oil emulsion under the combined action of magnetic field and nanoemulsion is 722 mPa·s. Compared with the viscosity of the heavy oil at 50 ℃, the viscosity is reduced by 53178 mPa·s, and the viscosity reduction rate is 98.66%.

The viscosity data comparison chart of heavy oil, Example 1, Example 2 and Example 3 under the conditions of shear rate γ =5 s ^-1 and temperature 50 °C is shown in FIG7 . Under the conditions of shear rate γ =5 s ^-1 and temperature 50 °C, the viscosity reduction rate of Example 1 is 25.23%, the viscosity reduction rate of Example 2 is 96.92%, and the viscosity reduction rate of Example 3 is 98.66%, indicating that under the combined action of magnetic field and nanoemulsion, the viscosity reduction effect of heavy oil will be more efficient.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including combining various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims (3)

1. The viscous oil emulsification viscosity-reducing method based on the combined action of a magnetic field and a nano emulsion is characterized in that the nano emulsion consists of white oil, paraffin, oleic acid, polyether amine D230, cetyl trimethyl ammonium bromide and deionized water, wherein the mass fraction of the cetyl trimethyl ammonium bromide is 0.4%; when preparing the nano emulsion, the dropper drops the water phase into the oil phase at a speed of about 0.1cm ³ per second; preparing nano emulsion with particle size of normal distribution and about 70% of particle size distribution of 2-12 nm; the permanent magnets are arranged along the inner wall of the stainless steel container, the shape and the size of the single permanent magnet are consistent, the magnetic field strength is the same, and the magnetic field strength is 150mT; the mass ratio of the thick oil to the nano emulsion is 3:7; the emulsification viscosity-reducing sequence is that three rows of permanent magnets are arranged along the inner wall of a stainless steel container, then quantitative thick oil is taken and placed in the stainless steel container, and then the prepared nano emulsion is added into the stainless steel container.

2. The method for emulsifying and viscosity-reducing thick oil by combining magnetic field and nano emulsion as set forth in claim 1, wherein the method comprises the following specific steps:

(1) Adding a certain amount of white oil, paraffin, oleic acid and polyether amine D230 into a beaker to form an oil phase together, stirring the beaker at a constant temperature of 65 ℃ by using a magnetic stirrer at a stirring speed of 600-800 r/min for 15min;

(2) Adding a certain amount of deionized water into another beaker, adding a certain amount of surfactant cetyl trimethyl ammonium bromide into the water phase, stirring the beaker with a magnetic stirrer at a constant temperature of 65 ℃ at a stirring speed of 600-800 r/min for 15min;

(3) Maintaining the beaker containing the oil phase at a constant temperature of 65 ℃, dripping the water phase at a speed of about 0.1cm ³ per second by using a dropper, stirring for 30min by using a magnetic stirrer, and standing for 3 hours to form a nano emulsion;

(4) Three rows of permanent magnets are arranged along the inner wall of a stainless steel container, quantitative thick oil is taken and placed in the stainless steel container, the temperature is kept at 55 ℃ and kept stand for 15min, so that a magnetic field fully acts with asphaltene and colloid in thick oil components, the prepared nano emulsion is added into the stainless steel container, the stainless steel container is kept stand for 10min at the constant temperature of 55 ℃, and the stirring is carried out by using an HJ-5 multifunctional stirrer at the stirring rotating speed of 1300-1500 r/min for 20min, so that the thick oil emulsion which is jointly acted by the magnetic field and the nano emulsion is obtained.

3. The method for emulsifying and viscosity-reducing thick oil under the combined action of a magnetic field and a nano emulsion as claimed in claim 1, wherein the thick oil emulsion prepared according to claim 1 has the viscosity of 722 mPa.s and the viscosity-reducing rate of 98.66% under the conditions of gamma=5s ^-1 and the temperature of 50 ℃.