High interfacial tension high interfacial modulus emulsion, and preparation method and application thereof

Abstract

The present application relates to the technical field of petroleum chemical industry, in particular to a kind of high interfacial tension high interfacial modulus emulsion and its preparation method and application.The emulsion is oil-in-water emulsion, including water phase and oil phase;Water phase includes modified nanosilica and water;Oil phase is catalytic rejection oil slurry, and the modified nanosilica is 2-[methoxy (polyoxyethylene) propyl] trimethoxysilane modified nanosilica containing 6-9EO.The emulsion has higher interfacial tension and interfacial modulus, and is used as profile control agent, has higher plugging efficiency, and can improve the recovery of crude oil.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, specifically to a high interfacial tension, high interfacial modulus emulsion, its preparation method, and its application. Background Technology

[0002] Chemical flooding technology is a key technology for improving the sweep efficiency of oil displacement systems in water-driven and chemical-driven oilfields. Chemical flooding increases the displacement pressure of the oil displacement system by injecting a flooding agent into the formation, thereby inhibiting the intrusion of the oil displacement system into high-permeability layers, fully utilizing the remaining oil, and thus expanding the sweep efficiency of the oil displacement system and the degree of utilization of formation crude oil.

[0003] Emulsions are an important chemical modulating and driving system. They primarily use surfactants as emulsifiers to emulsify the oil phase and water, forming a relatively stable modulating and driving system. However, in emulsions stabilized by surfactants or surfactant-nanoparticles, the presence of surfactants reduces the interfacial tension and elasticity of the oil-water interface to some extent. The plugging performance of emulsions in porous media is closely related to interfacial tension and elasticity; higher interfacial tension and elasticity result in greater flow resistance, stronger plugging power, and longer effective plugging time. Therefore, using emulsions stabilized with surfactants is not conducive to fully utilizing the long-term modulating and driving effect of emulsions.

[0004] Chinese patent document CN112143473A discloses an emulsion flood control agent and its preparation method. The emulsion flood control agent comprises the following components: an oil phase, an emulsifier, an interfacial film stabilizer, and the balance being water. The emulsifier is a surfactant complex system, including anionic, cationic, and nonionic surfactants. The interfacial film stabilizer is nanoparticles. The emulsifier used in this invention is an anionic / cationic / nonionic surfactant complex system. The synergistic effect of these three components makes residual oil easier to emulsify. Simultaneously, due to electrostatic interactions, the surfactants are more uniformly distributed on the oil-water interfacial film, which is beneficial for the formation and stability of the oil-in-water emulsion. Furthermore, the selected water-based nano-polysilicon particles are insensitive to the pH value of the system. The nanoparticles can form an ordered structural association with surfactant molecules on the oil-water interfacial film. This structure makes the emulsion more stable, preventing demulsification for 180 days, thus extending the effective period of the flood control operation. In this system, the emulsifier is a surfactant complex system, which reduces interfacial tension and elasticity, thereby reducing the sealing efficiency of the emulsion.

[0005] Chinese patent document CN112300768A discloses a nanoparticle-reinforced residue oil emulsion modifier and its preparation method. The modifier comprises an oil phase, nanosol, a surfactant, and water; wherein the surfactant includes fatty alcohol polyoxyethylene ether sulfonate, alkyl glycoside, and alkyl ammonium bromide. This modifier also requires the use of surfactants, which reduces interfacial tension and elasticity, thereby decreasing the emulsion's blocking efficiency.

[0006] Chinese patent document CN114231267A discloses an emulsified oil displacement agent, its preparation method, and its application. The preparation method includes: adding a silane coupling agent to a mixture of silica and toluene under heating conditions, sealing and stirring, and after the reaction, post-treatment to obtain silane coupling agent-modified silica; mixing the silane coupling agent-modified silica with toluene, heating and stirring, then adding polyoxyethylene ether, sealing, and continuing stirring, and after the reaction, post-treatment to obtain the emulsified oil displacement agent. This method of preparing the emulsified oil displacement agent is achieved through a two-step reaction involving silica, silane coupling agent, and polyoxyethylene ether. Compared with existing technologies, the process steps are simple, the principle is reliable, and the repeatability is high. It not only shortens the production cycle but also reduces energy consumption, conforming to the concepts of energy conservation, emission reduction, and green chemistry. This invention mainly utilizes modified nano-silica as an oil displacement agent, primarily leveraging modified nanomaterials for oil displacement. This invention utilizes the oil-in-water emulsion formed after emulsification as an oil displacement agent. It mainly utilizes the Jamin effect at the oil-water interface of the oil-in-water emulsion to block water channeling and increase the resistance to water flow. However, the magnitude of the Jamin effect is affected by the interfacial modulus. This invention mainly utilizes the role of modified nanomaterials in emulsifying oil and the influence of nanomaterials on the interfacial modulus. Nanomaterials do not directly play an oil displacement role, and therefore differ from this invention.

[0007] Therefore, there is an urgent need for a chemical modulator with high interfacial tension and high interfacial modulus to effectively improve the plugging efficiency and thus improve the oil recovery rate. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a high interfacial tension and high interfacial modulus emulsion, its preparation method, and its applications. The emulsion described in this invention possesses high interfacial tension and interfacial modulus, and when used as a modulator, it exhibits high plugging efficiency, thereby improving oil recovery.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, the present invention provides a method for preparing modified nano-silica, the method comprising the following steps: preparing an aqueous solution A of 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane containing EO linkages, and preparing a nano-silica hydrosol dispersion B; adding a portion of the aqueous solution A dropwise to the dispersion B, stirring, and then adding the remaining aqueous solution A, adjusting the pH, and stirring again.

[0011] Furthermore, the mass ratio of aqueous solution A to dispersion B is 1:1 to 10.

[0012] Furthermore, the mass ratio of 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane to water in aqueous solution A is 1:5-20.

[0013] Furthermore, the number of EO units in the 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane containing EO units is 6-15.

[0014] Further, a portion of the aqueous solution A is added dropwise to the dispersion B and stirred for 1-3 hours; after adding the remaining aqueous solution A, the pH value is adjusted to 9-11 with concentrated alkali solution, and stirred at 55-65℃ for 20-30 hours.

[0015] In a second aspect, the present invention provides a high interfacial tension and high interfacial modulus emulsion, wherein the emulsion is an oil-in-water emulsion comprising an aqueous phase and an oil phase; the aqueous phase comprises modified nano-silica and water; the oil phase is a catalytically slurry; and the modified nano-silica is prepared by the method for preparing modified nano-silica described in the first aspect above.

[0016] Furthermore, the mass ratio of the aqueous phase to the oil phase is 5-100:1-5.

[0017] Furthermore, the mass concentration of modified nano-silica in the aqueous phase is 0.5% to 5%.

[0018] Furthermore, the water is mineralized water; the mineralization degree of the mineralized water is 10,000-150,000 mg / L.

[0019] The third aspect of the present invention provides a method for preparing the high interfacial tension and high interfacial modulus emulsion described in the second aspect above, wherein the oil phase and the aqueous phase are stirred and mixed at a speed of 10,000 to 30,000 r / min.

[0020] The fourth aspect of this invention provides the high interfacial tension and high interfacial modulus emulsion described in the second aspect above, and the application of the emulsion prepared by the method described in the third aspect above in oilfield plugging and regulation.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The preparation method of the modified nano silica of the present invention can effectively adjust the hydrophilicity of nano silica, so that nano silica changes from strong hydrophilicity to weak hydrophilicity, thereby enabling it to be adsorbed on the oil-water interface.

[0023] 2. This invention disperses modified nano-silica sol in an aqueous phase. By modifying the surface of nano-silica, the drawback of nano-silica being too hydrophilic to effectively adsorb at the oil-water interface is overcome. The polyoxyethylene chain segments of the modified groups on the surface of the modified nano-silica are adsorbed at the oil-water interface through hydrogen bonding with hydroxyl and carboxylic acid groups in the external oil slurry, thereby stabilizing the oil-water interface and enhancing the stability of the emulsion.

[0024] 3. The emulsion of the present invention has high interfacial tension and interfacial modulus; at a temperature of 20°C and a shear rate of 7.34 s⁻¹, it exhibits these properties. -1 Under these conditions, the viscosity of the system can reach 64 mPa·s; the stability time at room temperature exceeds 60 days. When the emulsion of this invention is used for median flooding, it is effective for applications with permeability of 1000–3000 × 10⁻⁶ mPa·s. -3 μm 2 The drag coefficient of the sandstone core reached over 6.

[0025] Compared with surfactant-stabilized emulsions, the emulsion of this invention has higher plugging efficiency, greater plugging strength, and longer plugging duration; it also has better modulating effect. Detailed Implementation

[0026] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0027] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. Furthermore, it should be understood that when the terms "comprising" or "including" are used in this specification, they indicate the presence of features, steps, operations, and combinations thereof.

[0028] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0029] Unless otherwise specified, all reagents and materials used in the examples are commercially available or prepared using existing technologies; and all methods used are existing technologies unless otherwise specified.

[0030] Example 1

[0031] The preparation method of modified nano-silica includes the following steps:

[0032] (1) Measure 1.292 g of 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane with 6-9 EO chain segments into a beaker, add 7.752 g of 6 times the volume of deionized water to dilute and mix with the ligand, and stir thoroughly to obtain aqueous solution A;

[0033] (2) Measure 10g of nano-silica dispersion with a median particle size of 15nm and an effective content of 30%wt into a beaker, add 30ml of deionized water and stir for 5min to obtain dispersion B.

[0034] (3) Add half of the volume of aqueous solution A slowly to dispersion B under vigorous stirring, and stir at room temperature for 2 hours; then add the other half of aqueous solution A, adjust the pH of the reaction to 10 with concentrated NaOH, add 8.898 ml of deionized water, and stir the solution at 55°C for 22 hours.

[0035] (4) Centrifuge and wash the reaction solution to remove ungrafted ligands and reaction byproducts, and dry it to obtain modified silica.

[0036] The modified nano-silica obtained in this embodiment has a normal particle size distribution of 30–60 nm, with a median particle size of 40 nm. It exhibits good stability in brine with a mineralization of 100,000 mg / L and shows no flocculation or precipitation.

[0037] Example 2

[0038] (1) Measure 2.584 g of 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane with EO chain segments of 12-15 into a beaker, add 15.504 g of 6 times the volume of deionized water to dilute and mix with the ligand, and stir thoroughly to obtain aqueous solution A;

[0039] (2) Measure 10g of nano silica dispersion with a median particle size of 30nm and a mass fraction of 30% into a beaker, add 30ml of deionized water and stir for 5min to obtain dispersion B.

[0040] (3) Half of the volume of aqueous solution A was slowly added dropwise to dispersion B under vigorous stirring, and stirred at room temperature for 2 hours; then the other half of the ligand solution was added, and the pH of the reaction was adjusted to 10 with concentrated NaOH. 17.296 ml of deionized water was added, and the solution was stirred at 65°C for 26 hours.

[0041] (4) Centrifuge and wash the reaction solution to remove ungrafted ligands and reaction byproducts, and dry it to obtain modified silica.

[0042] The modified nano-silica obtained in this embodiment has a normal particle size distribution of 35–70 nm, with a median particle size of 45 nm. It exhibits good stability in brine with a mineralization of 100,000 mg / L and shows no flocculation or precipitation.

[0043] Example 3

[0044] The preparation method of modified nano-silica differs from that of Example 1 in that the mass ratio of aqueous solution A to dispersion is 1:1, and the mass ratio of 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane to water in aqueous solution A is 1:5; all other aspects are the same as in Example 1.

[0045] Example 4

[0046] The preparation method of modified nano-silica differs from that of Example 1 in that the mass ratio of aqueous solution A to dispersion is 1:10, and the mass ratio of 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane to water in aqueous solution A is 1:20; all other aspects are the same as in Example 1.

[0047] Example 5

[0048] The preparation method of modified nano silica differs from that of Example 1 in that, in step (3), half of the volume of aqueous solution A is slowly added dropwise to dispersion B under vigorous stirring, and stirred at room temperature for 3 hours; then the other half of aqueous solution A is added, and the pH of the reaction is adjusted to 11 with concentrated NaOH, 8.898 ml of deionized water is added, and the solution is stirred at 55°C for another 20 hours; all other steps are the same as in Example 1.

[0049] Example 6

[0050] The preparation method of modified nano silica differs from that of Example 1 in that, in step (3), half of the volume of aqueous solution A is slowly added dropwise to dispersion B under vigorous stirring, and stirred at room temperature for 1 hour; then the other half of aqueous solution A is added, and the pH of the reaction is adjusted to 9 with concentrated NaOH, 8.898 ml of deionized water is added, and the solution is stirred at 55°C for another 30 hours; all other steps are the same as in Example 1.

[0051] Example 7

[0052] A high interfacial tension and high interfacial modulus emulsion is disclosed, wherein the emulsion is an oil-in-water emulsion comprising an aqueous phase and an oil phase; the aqueous phase consists of modified nano-silica prepared in Example 1 and mineralized water, wherein the mass concentration of the modified nano-silica is 1%, and the mineralization of the mineralized water is 150,000 mg / L; the oil phase is a refinery catalytic cracking slurry, and the mass ratio of the aqueous phase to the oil phase is 19:1. The oil phase and the aqueous phase are thoroughly mixed and stirred at 15,000 r / min for 20 min to obtain the high interfacial tension and high interfacial modulus emulsion.

[0053] The resulting emulsion had an interfacial modulus of 27 mN / m and an oil-water interfacial tension of 66 mN / m. The packed permeability was 2720 × 10⁻⁶. -3 μm 2 The sand-filled pipe is first water-driven to measure the flow pressure, and then the emulsion is injected to measure the flow pressure, thereby calculating the resistance coefficient of the emulsion flowing in the porous medium to be 8.7.

[0054] Example 8

[0055] A high interfacial tension and high interfacial modulus emulsion is disclosed, wherein the emulsion is an oil-in-water emulsion comprising an aqueous phase and an oil phase. The aqueous phase consists of modified nano-silica prepared in Example 1 and mineralized water: the mass concentration of the modified nano-silica is 2.5%, and the mineralization degree of the mineralized water is 100,000 mg / L. The oil phase is a refinery catalytic cracking slurry, and the mass ratio of the aqueous phase to the oil phase is 97:3. The oil phase and the aqueous phase are thoroughly mixed and stirred at 10,000 r / min for 15 min to obtain the high interfacial tension and high interfacial modulus emulsion.

[0056] The resulting emulsion had an interfacial modulus of 33 mN / m and an oil-water interfacial tension of 66 mN / m. The emulsion remained stable at room temperature for 68 days without significant oil-water separation. The system viscosity was 21 mPa·s. The packed permeability was 1575 × 10⁻⁶. -3 μm 2 The sand-filled pipe is first water-driven to measure the flow pressure, and then the emulsion is injected to measure the flow pressure, thereby calculating the resistance coefficient of the emulsion flowing in the porous medium to be 9.5.

[0057] Example 9

[0058] A high interfacial tension and high interfacial modulus emulsion is disclosed, wherein the emulsion is an oil-in-water emulsion comprising an aqueous phase and an oil phase; the aqueous phase consists of modified nano-silica prepared in Example 1 and mineralized water, wherein the mass concentration of the modified nano-silica is 1%, and the mineralization degree of the mineralized water is 100,000 mg / L; the oil phase is a refinery catalytic cracking slurry, and the mass ratio of the aqueous phase to the oil phase is 5:1. The oil phase and the aqueous phase are thoroughly mixed and stirred at 20,000 r / min for 15 min to obtain the high interfacial tension and high interfacial modulus emulsion.

[0059] The resulting emulsion had an interfacial modulus of 30 mN / m and an oil-water interfacial tension of 63.8 mN / m. The emulsion remained stable at room temperature for 68 days without significant oil-water separation. The system viscosity was 64 mPa·s. The packing permeability was 1575 × 10⁻⁶. -3 μm 2 The sand-filled pipe is first water-driven to measure the flow pressure, and then the emulsion is injected to measure the flow pressure. The resistance coefficient of the emulsion flowing in the porous medium is calculated to be 11.6.

[0060] Example 10

[0061] A high interfacial tension and high interfacial modulus emulsion is disclosed, wherein the emulsion is an oil-in-water emulsion comprising an aqueous phase and an oil phase; the aqueous phase consists of modified nano-silica prepared in Example 1 and mineralized water, wherein the mass concentration of the modified nano-silica is 2% and the mineralization degree of the mineralized water is 100,000 mg / L; the oil phase is a refinery catalytic cracking slurry, and the mass ratio of the aqueous phase to the oil phase is 20:1. The oil phase and the aqueous phase are thoroughly mixed and stirred at 20,000 r / min for 15 min to obtain the high interfacial tension and high interfacial modulus emulsion.

[0062] The resulting emulsion had an interfacial modulus of 26 mN / m and an oil-water interfacial tension of 64.4 mN / m. The emulsion remained stable at room temperature for 68 days without significant oil-water separation. The system viscosity was 43 mPa·s. The packed permeability was 1575 × 10⁻⁶ m / s. -3 μm 2 For the sand-filled pipe, the flow pressure was first measured by water driving, and then the flow pressure was measured by injecting emulsion. The resistance coefficient of the emulsion in the porous medium was calculated to be 8.9.

[0063] Example 11

[0064] A high interfacial tension and high interfacial modulus emulsion is disclosed, wherein the emulsion is an oil-in-water emulsion comprising an aqueous phase and an oil phase. The aqueous phase consists of modified nano-silica prepared in Example 1 and mineralized water: the mass concentration of the modified nano-silica is 5%, and the mineralization degree of the mineralized water is 100,000 mg / L. The oil phase is a refinery catalytic cracking slurry, and the mass ratio of the aqueous phase to the oil phase is 5:1. The oil phase and the aqueous phase are thoroughly mixed and stirred at 30,000 r / min for 15 min to obtain the high interfacial tension and high interfacial modulus emulsion.

[0065] The resulting emulsion had an interfacial modulus of 34 mN / m and an oil-water interfacial tension of 63.4 mN / m. The emulsion remained stable at room temperature for 68 days without significant oil-water separation. The system viscosity was 61 mPa·s. The packing permeability was 3000 × 10⁻⁶. -3 μm 2 For the sand-filled pipe, the flow pressure was first measured by water driving, and then the flow pressure was measured by injecting emulsion. The resistance coefficient of the emulsion in the porous medium was calculated to be 12.5.

[0066] Comparative Example 1

[0067] The preparation method of modified nano-silica differs from that of Example 1 in that 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane with EO chain segments of 2-4 is used, while all other aspects are the same as in Example 1.

[0068] The median particle size of the obtained modified nano-silica was 34 nm. The modified nano-silica flocculated and precipitated in a brine solution with a salinity of 100,000 mg / L. This indicates that the shorter EO chain segments during synthesis affected the degree of surface modification of the nanomaterials and reduced the salt resistance of the modified nano-silica.

[0069] Comparative Example 2

[0070] The preparation method of modified nano silica differs from that of Example 2 in that the solution is stirred at 65°C for 16 hours in step (3), while the rest is the same as in Example 2.

[0071] The obtained modified nano-silica particles had a size of 20–150 nm. Significant flocculation occurred after 1 hour in a saline solution with a mineralization of 100,000 mg / L. This indicates that a short reaction time during synthesis affects the degree of surface modification of the nanomaterials and reduces their salt resistance.

[0072] Comparative Example 3

[0073] An emulsion, wherein the emulsion is an oil-in-water emulsion, differs from Example 8 in that the oil phase and the water phase are thoroughly mixed and stirred at 2000 r / min for 15 min, while all other aspects are the same as in Example 8.

[0074] The resulting emulsion exhibited rapid oil-water separation within 1 minute. This indicates that the adsorption of modified nanomaterials requires high-speed stirring; low-speed stirring cannot yield a stable emulsion.

[0075] Comparative Example 4

[0076] An emulsion, wherein the emulsion is an oil-in-water emulsion, comprising an aqueous phase and an oil phase; the aqueous phase comprises emulsifier OP-10, cationic polyacrylamide (relative molecular weight 10 million, cationicity 20%), and mineralized water with a mineralization of 100,000 mg / L; the mass concentration of the cationic polymer in the aqueous phase is 0.2%, and the mass concentration of emulsifier OP-10 is 2%; the oil phase is a catalytically slurry. The mass ratio of the aqueous phase to the oil phase is 90:10.

[0077] The method for preparing the above emulsion includes:

[0078] Add emulsifier OP-10 to water at a mass concentration of 2%; stir until the emulsifier is completely dissolved to obtain an aqueous phase; mix the obtained aqueous phase and oil phase at a mass ratio of 90:10 at 500 r / min to form an oil-in-water emulsion, which is the emulsion.

[0079] The resulting emulsion had an interfacial tension of 0.12 mN / m and an interfacial modulus of 1.2 mN / m. The permeability of the emulsion was 2700 × 10⁻⁶. -3 μm 2For the sand-filled pipe, the flow pressure was first measured by water driving, and then the flow pressure was measured by injecting emulsion. The resistance coefficient of the emulsion flow in the porous medium was calculated to be 5.1.

[0080] Comparing Example 8 with Comparative Example 8, it can be seen that the emulsion described in Example 4 of the present invention has a stronger blocking ability and resistance coefficient.

[0081] When the emulsion described in this embodiment of the invention is applied to oilfield plugging and regulation, the emulsion has higher plugging efficiency, greater plugging strength, and longer effective plugging period; the regulation effect is better, and it can significantly improve the recovery rate of crude oil.

[0082] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. An emulsion produced from modified nanosilica characterized in that, The emulsion is an oil-in-water emulsion, comprising an aqueous phase and an oil phase; the aqueous phase comprises modified nano-silica and water; the oil phase is a catalytically slurry; the preparation of the modified nano-silica includes the following steps: Prepare an aqueous solution A of 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane containing EO linkages, and then prepare a nano-silica hydrosol dispersion B. Add a portion of the aqueous solution A dropwise to the dispersion B, stir, and then add the remaining aqueous solution A. Adjust the pH and stir again. The mass ratio of aqueous solution A to dispersion B is 1:1~10. The volume ratio of 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane to water in aqueous solution A is 1:5-20; the number of EO units in the 2-[methoxy(polyoxyethylene)propyl]trimethoxysilane is 6-15. The median particle size range of the nano-silica is 15~30nm; Add a portion of the aqueous solution A dropwise to the dispersion B and stir for 1-3 hours; after adding the remaining aqueous solution A, adjust the pH value to 9-11 with concentrated alkali solution and stir at 55-65℃ for 20-30 hours.

2. The emulsion of claim 1, wherein, The water is mineralized water; the mineralization degree of the mineralized water is 10,000-150,000 mg / L.

3. The emulsion of claim 1, wherein, The mass ratio of the aqueous phase to the oil phase is 5~100:1~5.

4. The emulsion of claim 1, wherein, The mass concentration of modified nano-silica in the aqueous phase is 0.5%~5%.

5. Process for the preparation of the emulsion according to any one of claims 1 to 4, characterized in that, The oil phase and the water phase are stirred and mixed at 10,000 to 30,000 r / min.

6. The emulsion according to any one of claims 1-4, and the emulsion prepared by the method of claim 5, in oilfield plugging and regulation.