Specialty petroleum nano-flooding agents, their preparation methods and applications

Abstract

This invention discloses a special petroleum nano-dispersant, its preparation method, and its application, belonging to the field of petroleum extraction and storage technology. It is a water-based nano-dispersion system comprising water, a water-soluble polymer, and at least one surfactant. The water-soluble polymer is selected from one or more of the following: homopolymers or copolymers of C12-C22 alkyl poly(meth)acrylate, maleic anhydride-C12-C22 alkyl vinyl ether copolymers or their salts, acrylamide copolymers containing C12-C22 alkyl groups, and polyethylene glycol. The special petroleum nano-dispersant has an average hydrodynamic particle size of 10 nm-500 nm and possesses the dual functions of dispersing wax crystals and chemically modifying crude oil rheology. By weight percentage, the effective content of the water-soluble polymer is 5%-15%, the total content of the surfactant is 2%-15%, and the remainder is water. The water-soluble polymer is [missing information]. It can achieve efficient pour point depressant and viscosity reduction, and utilizes the dual functions of dispersing wax crystals and chemically modifying crude oil rheology to achieve synergistic improvement in crude oil flowability.

Description

Technical Field

[0001] This invention belongs to the field of petroleum extraction and storage technology, specifically relating to special petroleum nano-explosives, their preparation methods, and applications. Background Technology

[0002] During crude oil extraction and pipeline transportation, when the temperature drops below the wax precipitation point, the dissolved wax components (mainly C25–C30 n-alkanes) crystallize out in the form of plates or needles, gradually forming a three-dimensional network structure that encapsulates the liquid hydrocarbons. This causes a sharp decrease in crude oil fluidity and an increase in the pour point, and in severe cases, even leads to pipeline blockages and production shutdowns. This problem is particularly prominent for high-wax crude oils and high-pour-point crude oils.

[0003] To address the aforementioned issues, the addition of chemical pour point depressants is widely adopted both domestically and internationally to improve the low-temperature fluidity of crude oil. Existing pour point depressants mainly include oil-soluble polymers such as ethylene-vinyl acetate copolymer (EVA), polyacrylates, and maleic anhydride copolymers. Their mechanism of action generally involves co-crystallizing or adsorbing with waxes, altering the morphology and size of wax crystals, and preventing the formation of three-dimensional networks. However, these traditional pour point depressants generally suffer from the following shortcomings: First, existing oil-soluble pour point depressants mostly require the use of aromatic solvents such as benzene, toluene, and xylene for dissolution and transportation. During on-site addition, volatile organic compounds are released, posing significant hazards to operators and the environment, making it difficult to meet increasingly stringent environmental regulations. Second, traditional pour point depressants have relatively limited functions, mainly targeting the problem of increased pour point caused by wax crystal precipitation. For heavy oil containing high wax and high asphaltene with extremely high viscosity, the viscosity-reducing effect is limited, often requiring the addition of other viscosity depressants, increasing process complexity and usage costs. In addition, existing commercial pour point depressants are mostly micron-sized emulsions or suspensions with large particle sizes and limited specific surface areas, resulting in slow dispersion and low utilization rates in crude oil, requiring higher addition amounts to achieve the desired effect.

[0004] In recent years, although some water-based pour point depressants have been reported, replacing aromatic solvents with water and reducing environmental risks, most of these formulations only achieve solvent replacement and do not consider the dispersion scale of the active ingredients at the microstructural level. Their active components still exist in the form of micron-sized droplets or particles, and there is no qualitative breakthrough in application performance. At the same time, no technical solution has been found in the existing water-based systems to unify pour point depressing and viscosity reducing functions in the same formulation at the nanoscale.

[0005] Therefore, there is an urgent need to develop a new type of crude oil flow improver that is both environmentally friendly and capable of achieving efficient pour point depressant and viscosity reduction through nanoscale dispersion. Summary of the Invention

[0006] The purpose of this invention is to provide a special petroleum nano-flooding agent, its preparation method and application. The flooding agent exists in the form of a nano-scale dispersion and has the dual functions of depressing pour point and reducing viscosity.

[0007] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: This special petroleum nano-dispersant is a water-based nano-dispersion system comprising water, a water-soluble polymer, and at least one surfactant. The water-soluble polymer is selected from one or more of the following: homopolymers or copolymers of C12-C22 alkyl poly(meth)acrylate, maleic anhydride-C12-C22 alkyl vinyl ether copolymers or their salts, acrylamide copolymers containing C12-C22 alkyl groups, and polyethylene glycol. The average hydrodynamic particle size of this special petroleum nano-dispersant is 10 nm to 500 nm, and it has the dual functions of dispersing wax crystals and chemically modifying the rheological properties of crude oil.

[0008] In one or more embodiments of the present invention, the effective content of the water-soluble polymer is 5%-15% by weight, the total content of the surfactant is 2%-15%, and the balance is water.

[0009] In one or more embodiments of the present invention, the water-soluble polymer is: polyoctadecyl methacrylate emulsion; or sodium salt of maleic anhydride-octadecyl methacrylate copolymer; or AMPS-acrylamide-hexadecyl methacrylate terpolymer; or polyethylene glycol PEG-6000.

[0010] In one or more embodiments of the present invention, the surfactant is selected from at least one of fatty alcohol polyoxyethylene ether, sodium dodecyl sulfonate, alkyl phosphate betaine, rhamnolipid, isomeric alcohol polyoxyethylene ether, sorbitan monooleate, and polysorbate.

[0011] In one or more embodiments of the present invention, an adjuvant is further included, said adjuvant being at least one selected from ethylene glycol butyl ether, propylene glycol, methyl oleate, hydroxypropyl-β-cyclodextrin, and sodium citrate.

[0012] A method for preparing the above-mentioned special petroleum nano-flooding agent includes the following steps: mixing water-soluble polymer, surfactant and water in a specified amount at 40℃-80℃ at a speed of 500rpm-1000rpm for 0.5 hours-3 hours to obtain the special petroleum nano-flooding agent.

[0013] In one or more embodiments of the present invention, after stirring and mixing, the particles are further processed by a high-speed homogenizer at 10,000 rpm to 15,000 rpm for 1 to 3 minutes to refine the particle size to 30 nm to 200 nm.

[0014] Application of a special petroleum nano-flooding agent prepared by the above-described special petroleum nano-flooding agent or by the above-described method in crude oil pour point reduction and viscosity reduction.

[0015] In one or more embodiments of the present invention, the special petroleum nano-explosive agent is added at a rate of 0.1%-1.0% of the crude oil mass, and the crude oil temperature is 5°C-10°C higher than its wax precipitation point when added, and shear mixing at 500 rpm-1000 rpm is applied.

[0016] In one or more embodiments of the present invention, the special petroleum nano-flooding agent reduces the pour point of crude oil by 6°C-18°C and reduces the viscosity of heavy oil by more than 70%.

[0017] Compared with existing technologies, the special petroleum nano-flooding agent, its preparation method, and its application of the present invention use water as a medium, completely eliminating aromatic solvents, making it environmentally friendly and pollution-free; by constructing a 10nm-500nm nano-dispersion system, it significantly increases the specific surface area and interfacial activity, achieving efficient pour point depressant and viscosity reduction even with low addition amounts; and by utilizing the dual functions of dispersing wax crystals and chemically modifying crude oil rheology, it solves the problem of existing pour point depressants having a single function and requiring separate addition of viscosity reducers, thus achieving synergistic improvement in crude oil fluidity. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the preparation process of the nano-draining agent in an embodiment of the present invention; Figure 2 This is a schematic diagram of the nano-drive mechanism in an embodiment of the present invention; Figure 3 This is a process flow diagram of the application of nano-drive agent in an embodiment of the present invention. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0021] Particle size testing method: Dynamic light scattering (DLS) was used. The average hydrodynamic particle size (Z-average particle size) and particle size distribution of the samples were determined using a Malvern Zetasizer Nano ZS90 nanoparticle size and Zeta potential analyzer at 25℃ and a scattering angle of 90°.

[0022] Pour point reduction test: The pour point of crude oil samples before and after the addition of nano-explosive was determined according to SY / T 0541-2009 "Crude Oil Pour Point Determination Method", and the pour point reduction value was calculated.

[0023] Viscosity reduction effect test: A rotational viscometer was used at a shear rate of 10 s⁻¹. -1 Under the condition that the temperature is 10°C higher than the pour point of crude oil, the apparent viscosity of crude oil before and after the addition of nano-flooding agent is measured, and the viscosity reduction rate is calculated.

[0024] Example 1: This example is a preparation method of a general environmentally friendly nano-catalyst. The formula by weight percentage is as follows: 25% water-soluble polymethyl methacrylate (PMA) emulsion, 8% fatty alcohol polyoxyethylene ether AEO-9, 5% ethylene glycol butyl ether, 2% sodium dodecyl sulfonate SDS, and 60% deionized water.

[0025] Preparation method: Add the above components to the reaction vessel according to the ratio, stir and mix at 800 rpm for 1 hour under constant temperature of 50℃, adjust the pH to 7.5 with sodium hydroxide solution, filter through a 200-mesh filter to obtain a bluish translucent liquid, which is the nano-catalyst.

[0026] Particle size test: The average hydrodynamic particle size was 85 nm and the particle size distribution (PDI) was 0.15, as determined by DLS.

[0027] Pour point reduction application: Take low-wax crude oil with a wax content of 8.5% and a wax precipitation point of 38℃, heat it to 45℃, add 0.2% of the nano-flooding agent of this embodiment by mass of crude oil, mix it evenly under shear at 800 rpm, and measure the pour point after cooling; the original pour point of crude oil was 28℃, and the pour point after treatment was 19℃, a decrease of 9℃.

[0028] Example 2: This example is a method for preparing a nano-flooding agent for high-wax crude oil. The formula by weight percentage is as follows: 30% sodium salt of maleic anhydride-octadecyl acrylate copolymer, 3% hydroxypropyl-β-cyclodextrin, 5% alkyl phosphate betaine, 1% sodium citrate, and 61% deionized water.

[0029] Preparation method: Add the above components into the reaction vessel according to the ratio, stir and mix at a rate of 600 rpm for 2 hours under constant temperature of 60℃, and cool to room temperature to obtain the nano-drive agent.

[0030] Particle size test: The average hydrodynamic particle size was 120 nm and the particle size distribution (PDI) was 0.18, as determined by DLS.

[0031] Pour point reduction application: High-wax crude oil with a wax content of 18.2% and a wax precipitation point of 45℃ was heated to 52℃, and 0.3% (by weight) of the nano-flooding agent of this embodiment was added. The mixture was thoroughly mixed under shear at 700 rpm, and the pour point was measured after cooling. The original pour point of the crude oil was 36℃, and the pour point after treatment was 24℃, a decrease of 12℃.

[0032] Salt tolerance test: In simulated formation water with a salinity of 180,000 mg / L, the nano-flooding agent in this embodiment remained stable without stratification and the particle size did not increase significantly, indicating that it has excellent salt tolerance.

[0033] Example 3: This example is a method for preparing a high-viscosity oil-type nano-draining agent. The formula by weight percentage is: 35% AMPS-acrylamide-hexadecyl acrylate terpolymer, 2% rhamnose lipolipide, 4% isomeric alcohol polyoxyethylene ether, 6% propylene glycol, and 53% deionized water.

[0034] Preparation method: Add the above components into the reaction vessel according to the ratio, emulsify and stir at 1000 rpm for 3 hours under constant temperature of 70℃, then further process with a high-speed homogenizer at 12000 rpm for 2 minutes, and obtain the nano-expelling agent after homogenization and filtration.

[0035] Particle size analysis: DLS measurement showed an average hydrodynamic particle size of 65 nm and a particle size distribution (PDI) of 0.11. Cryo-transmission electron microscopy (Cryo-TEM) confirmed that the particles in the sample were uniformly spherical, with the particle size mainly concentrated in the range of 40 nm to 100 nm.

[0036] Application of pour point and viscosity reduction: Take a high pour point crude oil with a pour point of 48℃, a wax content of 12.5%, and a resin and asphaltenes content of 22%, heat it to 56℃, add 0.5% of the nano-flooding agent of this embodiment by mass of crude oil, and mix it evenly under shear at 900 rpm; after treatment, the pour point of crude oil drops to 32℃, a decrease of 16℃; the apparent viscosity is measured at 42℃, which drops from 18500 mPa·s before treatment to 3800 mPa·s, with a viscosity reduction rate of 79.5%.

[0037] Example 4: This example is a simplified laboratory preparation method for a nano-drive agent. The formula by weight percentage is: polyethylene glycol PEG-6000 15%, Span-80 5%, Tween-80 5%, methyl oleate 10%, and deionized water 65%.

[0038] Preparation method: Add the above components into a container according to the ratio, stir and melt at 500 rpm at 60℃ for 1 hour, and cool to room temperature to obtain the nano-drive agent.

[0039] Particle size test: The average hydrodynamic particle size was 210 nm and the particle size distribution (PDI) was 0.20, as determined by DLS.

[0040] Pour point reduction application: Take low pour point crude oil with a pour point of 15℃ and a wax content of 4.2%, heat it to 28℃, add 0.8% of the nano-flooding agent of this embodiment by mass of crude oil, and mix evenly under shear at 600 rpm; after treatment, the pour point of crude oil drops to 10℃, a decrease of 5℃.

[0041] Example 5: This example is an environmental performance test experiment. The nano-catalysts obtained in Examples 1-4 were subjected to biodegradation rate testing (OECD 301B method, 28 days) and heavy metal content detection (ICP-MS method). The results show that the biodegradation rate of the products in each example is ≥91.5%, and heavy metals (lead, cadmium, mercury, chromium) were not detected, which meets the environmental protection requirements of SY / T 5767-2016.

[0042] Example 6: This example is a comparative experiment on the effects of different addition amounts. Using the nano-flooding agent prepared in Example 3 as the test object, the effects of different addition amounts on reducing pour point and viscosity of the same high-pour-point-weight oil sample were compared. The results are shown in the table below:

[0043] As shown in the table above, the best cost-effectiveness can be achieved when the addition amount is in the range of 0.3-0.6wt%. When the addition amount is increased to 1.0wt%, the effect tends to saturate, but it is still within the effective range.

[0044] Example 7: This example is an experiment on the effects of addition temperature and shear conditions. Using the nano-flooding agent prepared in Example 2 as the test object, the same high-wax crude oil was compared under different addition temperatures and shear conditions. The results show that the best pour point reduction effect can be obtained when the nano-flooding agent is added at a temperature 5℃-10℃ higher than the wax precipitation point and sheared at 500 rpm-1000 rpm. If the temperature is too low, the nano-flooding agent will be unevenly dispersed, and the pour point reduction effect will decrease by about 40%. When no shear is applied, the pour point reduction effect will decrease by about 55%, which fully verifies the rationality of the application conditions.

[0045] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0046] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A special petroleum nano-flooding agent, characterized in that, It is a water-based nano-dispersion system comprising water, a water-soluble polymer, and at least one surfactant; the water-soluble polymer is selected from one or more of the following: homopolymers or copolymers of C12-C22 alkyl poly(meth)acrylate, maleic anhydride-C12-C22 alkyl vinyl ether copolymers or their salts, acrylamide copolymers containing C12-C22 alkyl groups, and polyethylene glycol; the special petroleum nano-draining agent has an average hydrodynamic particle size of 10 nm-500 nm and has the dual functions of dispersing wax crystals and chemically modifying the rheological properties of crude oil.

2. The special petroleum nano-flooding agent according to claim 1, characterized in that, The effective content of the water-soluble polymer is 5%-15% by weight, the total content of the surfactant is 2%-15%, and the balance is water.

3. The special petroleum nano-flooding agent according to claim 1, characterized in that, The water-soluble polymer is: polyoctadecyl methacrylate emulsion; or sodium salt of maleic anhydride-octadecyl methacrylate copolymer; or AMPS-acrylamide-hexadecyl methacrylate terpolymer; or polyethylene glycol PEG-6000.

4. The special petroleum nano-flooding agent according to claim 1, characterized in that, The surfactant is selected from at least one of fatty alcohol polyoxyethylene ether, sodium dodecyl sulfonate, alkyl phosphate betaine, rhamnolipid, isomeric alcohol polyoxyethylene ether, sorbitan monooleate, and polysorbate.

5. The special petroleum nano-flooding agent according to claim 1, characterized in that, It also includes an adjuvant, said adjuvant being at least one selected from ethylene glycol butyl ether, propylene glycol, methyl oleate, hydroxypropyl-β-cyclodextrin, and sodium citrate.

6. A method for preparing the special petroleum nano-flooding agent as described in claim 1, characterized in that, The process includes the following steps: mixing the water-soluble polymer, surfactant, and water in the prescribed amounts at 40℃-80℃ at a speed of 500rpm-1000rpm for 0.5 hours-3 hours to obtain the special petroleum nano-explosive agent.

7. The preparation method according to claim 6, characterized in that, After stirring and mixing, the particles are further processed using a high-speed homogenizer at 10,000 rpm to 15,000 rpm for 1 to 3 minutes to refine the particle size to 30 nm to 200 nm.

8. The application of a special petroleum nano-flooding agent prepared using any one of claims 1-5 or the method described in claim 6 or 7 in the dewaxing and viscosity reduction of crude oil.

9. The application according to claim 8, characterized in that, The special petroleum nano-explosive agent is added at a rate of 0.1%-1.0% of the crude oil mass, and the crude oil temperature is 5℃-10℃ higher than its wax precipitation point when added, and shear mixing is applied at 500 rpm-1000 rpm.

10. The application according to claim 8, characterized in that, The special petroleum nano-flooding agent reduces the pour point of crude oil by 6℃-18℃ and reduces the viscosity of heavy oil by more than 70%.

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