Preparation method of polyurethane-coated sustained-release capsule polymer

Abstract

The invention belongs to the technical field of oil and gas field development engineering, and provides a preparation method of a polyurethane-coated sustained-release capsule polymer. The preparation method comprises the following steps: adding a polyurethane prepolymer into base oil, and stirring at 20-30 DEG C and 800-1200 r / min until the polyurethane prepolymer is uniformly dispersed to obtain a base oil solution of the polyurethane prepolymer; the preparation method comprises the following steps: adding an emulsifier into deionized water, then adding into a base oil solution of a polyurethane prepolymer, and stirring at 20-30 DEG C and 800-1200 r / min for 0.5 h to form a uniform and stable mixed emulsion 1; adding a polymer emulsion into the mixed emulsion 1, and stirring at 20-30 DEG C and 800-1200 r / min for 0.5 h to form a uniform and stable mixed emulsion 2; and adding a polyol aqueous solution into the mixed emulsion 2, and carrying out a stirring reaction at 40-50 DEG C and 800-1200 r / min for 4-5 h to obtain the polyurethane-coated sustained-release capsule polymer. The process is simple, and the prepared sustained-release capsule polymer has good dispersibility in an aqueous solution, can slowly release internal effective components, and has great application potential in the aspect of deep targeted tackifying of conventional oil reservoirs.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field development engineering, and particularly relates to a method for preparing a polyurethane-coated sustained-release capsule polymer. Background Art

[0002] Polymer flooding is an important technology for improving oil recovery. Its basic principle is to increase the viscosity of the displacement fluid, thereby adjusting the mobility ratio of the displacement phase to the crude oil and expanding the swept volume of the displacement phase. Polymer flooding technology has been widely used in my country's oil fields. However, there are currently two problems: the viscosity of the displacement fluid is easily affected by the shear of the formation rock, resulting in viscosity loss, and the displacement fluid injection pressure is high.

[0003] To solve the above problems, Chinese patent document CN116003705A discloses a preparation method and application of a nano-network structure delayed viscosity polymer emulsion, which provides a nano-network structure delayed viscosity polymer emulsion, wherein the core is polymerized with nano-silicon dioxide, double-bond silane coupling agent, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid as monomer molecules, and the protective shell is formed by azobisisobutyronitrile initiating propylene-1,3-sultone, which can be pumped and delayed in ultra-low permeability and complex fault block sandstone reservoirs, but the shell material used is relatively expensive, which limits its application in actual production. In addition, Chinese patent document CN202410209335 discloses a capsule polymer for oil displacement and its preparation method and application, wherein the core uses polyacrylamide emulsion, the shell is environmentally friendly calcium alginate, which is obtained by cross-linking sodium alginate and calcium ions, and the calcium alginate coating is repeated to form capsule polymers of different thicknesses and densities, but its shear resistance and sustained release performance are not strong enough, especially under high temperature reservoir conditions.

[0004] Therefore, it is of great significance to develop a capsule polymer for oil displacement with simple synthesis process and strong shear resistance in high-temperature reservoirs. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for preparing a polyurethane-coated sustained-release capsule polymer. The present invention uses polyurethane as a shell material to microencapsulate a polymer emulsion, selects biomass polyol sorbitol as a polyurethane chain extender, and can control the release of the core polymer to a great extent; the polymer is wrapped in a microcapsule, and by controlling the release temperature and release rate of the polymer, the polymer can be more easily injected into the formation and can achieve the effect of release and viscosity enhancement in the far well formation.

[0006] To achieve the above object, the present invention adopts the following technical solution: A method for preparing a polyurethane-coated sustained-release capsule polymer, comprising the following steps: S1: adding the polyurethane prepolymer to the base oil, stirring at 20-30°C and 800-1200 r / min until the mixture is uniformly dispersed, to obtain a base oil solution of the polyurethane prepolymer; S2: Add the emulsifier to deionized water, and then add it to the base oil solution of the polyurethane prepolymer in S1, and stir for 0.5 h at 20-30° C. and 800-1200 r / min to form a uniform and stable mixed emulsion 1; S3: Add the polymer emulsion to the mixed emulsion 1 of S2, and stir for 0.5 h at 20-30°C and 800-1200 r / min to form a uniform and stable mixed emulsion 2; S4: Add polyol aqueous solution to the mixed emulsion 2 of S3, stir and react for 4-5 hours at 40-50° C. and 800-1200 r / min to obtain a polyurethane-coated sustained-release capsule polymer.

[0007] Furthermore, in the above step S1, the ratio of the mass of the polyurethane prepolymer to the mass of the base oil is 0.5-1:1.

[0008] Furthermore, in the above step S2, the ratio of the mass of the emulsifier to the mass of the base oil in step S1 is 0.01-0.15:1, and the ratio of the mass of the deionized water to the mass of the base oil in step S1 is 1:0.5-1.5.

[0009] Furthermore, in the above step S3, the ratio of the mass of the polymer emulsion to the mass of the mixed emulsion 1 is 1:3.6-4.

[0010] Furthermore, in the above step S4, the ratio of the mass of the polyol aqueous solution to the mass of the mixed emulsion 2 is 1:180-200.

[0011] Furthermore, the prepolymer monomers of the above-mentioned polyurethane prepolymer are isophorone diisocyanate and polyethylene glycol; the above-mentioned base oil is any one or more of white oil, kerosene, and liquid paraffin; the above-mentioned emulsifier is any one or more of MOA-9, MOA-3, Span80, Span85, Tween80, Tween60, and OP-10; the comonomer of the above-mentioned polymer is any one or more of acrylamide, 2-acrylamide-2-methylpropane sulfonic acid, acrylic acid, styrene sulfonic acid, and N-alkylmaleimide; and the above-mentioned polyol is any one or more of D-sorbitol and L-sorbitol.

[0012] A polyurethane-coated sustained-release capsule polymer is prepared by the above-mentioned preparation method.

[0013] The application of the above-mentioned polyurethane-coated sustained-release capsule polymer in oil displacement.

[0014] The technical features and beneficial effects of the present invention are as follows: The present invention uses sorbitol as a chain extender for a polyurethane-coated sustained-release capsule polymer for the first time. Compared with commonly used petroleum-based chain extenders from non-renewable resources, sorbitol is easily available, environmentally friendly and renewable.

[0015] The present invention uses sorbitol as a chain extender to microencapsulate the P (AM AA) emulsion. On the one hand, the polymer molecules are wrapped, and the viscosity thereof cannot be released, making it easier to inject; on the other hand, the inner core polymer is protected from shearing of the formation, and the release of the inner core polymer is effectively controlled. After the inner core polymer is injected into the formation, the capsule polymer is affected by the formation temperature, and the shell layer swells and ruptures, and the inner core polymer is released, thereby achieving the goal of slow release and viscosity increase.

[0016] The capsule polymer of the present invention has a simple synthesis process, and its shear resistance can be enhanced by regulating the components of the comonomers of the core polymer.

[0017] The microcapsule emulsion prepared by the present invention has high long-term stability, the capsule polymer has good dispersibility in aqueous solution, and can slowly release the effective ingredients inside, and has great application potential in deep targeted viscosity enhancement of conventional oil reservoirs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 These are the infrared spectra of polyurethane prepolymer, P(AM AA) emulsion, and SO8.

[0019] Figure 2 This is the infrared spectrum of SO4, SO6, SO8 and SO10.

[0020] Figure 3 It has delayed viscosity increasing properties for SO4, SO6, SO8 and SO10.

[0021] Figure 4 The effect of different trigger temperatures on the viscosity-increasing properties of SO4, SO6, SO8 and SO10.

[0022] Figure 5 SEM images of SO4 (a), SO6 (b), SO8 (c), and SO10 (d).

[0023] Figure 6 These are the particle size distribution curves of P(AM AA), SO4, SO6, SO8, and SO10.

[0024] Figure 7 The viscosity of SO8, BDO4 and BDO8 changes with time at 65°C and 500rpm. DETAILED DESCRIPTION

[0025] The present invention is described in detail below by way of examples to make the features and advantages of the present invention clearer. However, it should be noted that the examples are used to understand the concept of the present invention, and the scope of the present invention is not limited to the examples listed herein.

[0026] The "parts" mentioned in the present invention are all parts by mass.

[0027] The polymer emulsion used in the embodiments of the present invention is prepared according to the following method: 50 parts of acrylamide and 18 parts of acrylic acid are dissolved in 32 parts of deionized water at 30°C, the pH value is adjusted to 7.5 with sodium hydroxide, 0.42 parts of azobisisobutylamidine hydrochloride are added, and stirred evenly to obtain a water phase; 3 parts of Span80 and 2 parts of Tween80 are added dropwise to 92 parts of white oil (5#), stirred for 30 minutes at 30°C to emulsify, and an oil phase is obtained; the obtained water phase is added dropwise to the obtained oil phase under stirring at 30°C, the dropping speed is 5mL / min, the stirring speed during the dropping process is 350r / min, nitrogen is passed through during the dropping process of the water phase for deoxygenation, and the nitrogen flow rate is 1L / min, then the temperature is raised to 46°C, the stirring speed is raised to 800r / min, the nitrogen is continued to be passed through for 50 minutes, and the reaction is carried out at a constant temperature for 2.5 hours to obtain a polymer emulsion, which is recorded as P(AMAA). The polymer content in the polymer emulsion is 34wt%, and the viscosity average molecular weight is 15 million.

[0028] The polyurethane prepolymer (prepolymer monomers are isophorone diisocyanate and polyethylene glycol) used in the examples of the present invention was purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd., CAS No. 103837-45-2.

[0029] Embodiment 1: This embodiment provides a method for preparing a polyurethane-coated sustained-release capsule polymer, the steps are as follows: 75 parts of polyurethane prepolymer were added to 100 parts of white oil (5#), and stirred at 25°C and 1000 r / min until uniformly dispersed to obtain a white oil solution of polyurethane prepolymer; 10 parts of Span80 were added to 100 parts of deionized water, and then dropped into the obtained white oil solution of polyurethane prepolymer, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 1; 75 parts of P (AM AA) emulsion were added to the obtained mixed emulsion 1, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 2; 2 parts of 4wt% D-sorbitol aqueous solution were added to the obtained mixed emulsion 2, and stirred at 50°C and 1000 r / min for 4 h to obtain a polyurethane-coated sustained-release capsule polymer, recorded as SO4.

[0030] Embodiment 2: This embodiment provides a method for preparing a polyurethane-coated sustained-release capsule polymer, the steps are as follows: 75 parts of polyurethane prepolymer were added to 100 parts of white oil (5#), and stirred at 25°C and 1000 r / min until uniformly dispersed to obtain a white oil solution of polyurethane prepolymer; 10 parts of Span80 were added to 100 parts of deionized water to obtain an aqueous solution of Span80; the obtained aqueous solution of Span80 was added dropwise to the obtained white oil solution of polyurethane prepolymer, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 1; 75 parts of P (AM AA) emulsion were added to the obtained mixed emulsion 1, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 2; 2 parts of 6wt% D-sorbitol aqueous solution were added to the obtained mixed emulsion 2, and stirred at 50°C and 1000 r / min for 4 h to obtain a polyurethane-coated sustained-release capsule polymer, recorded as SO6.

[0031] Embodiment 3: This embodiment provides a method for preparing a polyurethane-coated sustained-release capsule polymer, the steps are as follows: 75 parts of polyurethane prepolymer were added to 100 parts of white oil (5#), and stirred at 25°C and 1000 r / min until uniformly dispersed to obtain a white oil solution of polyurethane prepolymer; 10 parts of Span80 were added to 100 parts of deionized water to obtain an aqueous solution of Span80; the obtained aqueous solution of Span80 was added dropwise to the obtained white oil solution of polyurethane prepolymer, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 1; 75 parts of P(AM AA) emulsion were added to the obtained mixed emulsion 1, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 2; 2 parts of 8wt% D-sorbitol aqueous solution were added to the obtained mixed emulsion 2, and stirred at 50°C and 1000 r / min for 4 h to obtain a polyurethane-coated sustained-release capsule polymer, recorded as SO8.

[0032] Embodiment 4: This embodiment provides a method for preparing a polyurethane-coated sustained-release capsule polymer, the steps are as follows: 75 parts of polyurethane prepolymer were added to 100 parts of white oil (5#), and stirred at 25°C and 1000 r / min until uniformly dispersed to obtain a white oil solution of polyurethane prepolymer; 10 parts of Span80 were added to 100 parts of deionized water to obtain an aqueous solution of Span80; the obtained aqueous solution of Span80 was added dropwise to the obtained white oil solution of polyurethane prepolymer, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 1; 75 parts of P (AM AA) emulsion were added to the obtained mixed emulsion 1, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 2; 2 parts of a 10wt% D-sorbitol aqueous solution were added to the obtained mixed emulsion 2, and stirred at 50°C and 1000 r / min for 4 h to obtain a polyurethane-coated sustained-release capsule polymer, recorded as SO10.

[0033] Embodiment 5: This embodiment provides a method for preparing a polyurethane-coated sustained-release capsule polymer, the steps are as follows: 75 parts of polyurethane prepolymer were added to 100 parts of white oil (5#), and stirred at 25°C and 1000 r / min until uniformly dispersed to obtain a white oil solution of polyurethane prepolymer; 10 parts of Span80 were added to 100 parts of deionized water to obtain an aqueous solution of Span80; the obtained aqueous solution of Span80 was added dropwise to the obtained white oil solution of polyurethane prepolymer, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 1; 75 parts of P (AM AA) emulsion were added to the obtained mixed emulsion 1, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 2; 2 parts of 4wt% 1,4-butanediol aqueous solution were added to the obtained mixed emulsion 2, and stirred at 50°C and 1000 r / min for 4 h to obtain a polyurethane-coated sustained-release capsule polymer, recorded as BDO4.

[0034] Embodiment 6: This embodiment provides a method for preparing a polyurethane-coated sustained-release capsule polymer, the steps are as follows: 75 parts of polyurethane prepolymer were added to 100 parts of white oil (5#), and stirred at 25°C and 1000 r / min until uniformly dispersed to obtain a white oil solution of polyurethane prepolymer; 10 parts of Span80 were added to 100 parts of deionized water to obtain an aqueous solution of Span80; the obtained aqueous solution of Span80 was added dropwise to the obtained white oil solution of polyurethane prepolymer, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 1; 75 parts of P(AM AA) emulsion were added to the obtained mixed emulsion 1, and stirred at 25°C and 1000 r / min for 0.5 h to form a uniform and stable mixed emulsion 2; 2 parts of 8wt% 1,4-butanediol aqueous solution were added to the obtained mixed emulsion 2, and stirred at 50°C and 1000 r / min for 4 h to obtain a polyurethane-coated sustained-release capsule polymer, recorded as BDO8.

[0035] Characterization of Polyurethane Coated Sustained Release Capsule Polymers: Infrared spectra of polyurethane prepolymer, P(AM AA) emulsion, SO8 Figure 1 The FTIR spectrum of the polyurethane prepolymer is shown at 2269 cm -1 There is a strong absorption peak of NCO group at 2851~2963 cm -1 The absorption peak at 177° is consistent with the -CH 3 and -CH 2 -About, 1726 cm -1 and 1530 cm -1 The absorption peak at 1658 cm-1 is related to the C=O and NH in the carbamate bond. In the FTIR spectrum of P(AM AA) emulsion, the strong absorption peak at 1658 cm-1 is attributed to the stretching vibration of C=O on the amide group, and the strong absorption peak at 1608 cm-1 is attributed to the stretching vibration of C=O on the amide group. -1 and 1405 cm -1 The absorption peak at 1658 cm is attributed to the symmetric and antisymmetric stretching vibration of the COO- group, indicating the presence of the COO- group of acrylic acid on the molecular chain. -1 、1608 cm -1 and 1405 cm -1 Three absorption peaks.

[0036] The infrared spectra of SO4, SO6, SO8 and SO10 are as follows Figure 2 As shown in the figure, the absorption peak representing P(AM AA) emulsion can be observed. 1726 cm -1 、1530 cm -1 and 1240 cm -1The absorption peaks at 1100 cm -1 The peaks near 890 cm-1 are attributed to the C-OH stretching vibration of D-sorbitol. -1 The peak at is attributed to the bending vibration within the OH bond plane.

[0037] The delayed viscosity test method is: use a digital rotational viscometer (NDJ-9S, rotor No. 1, 60r / min) to measure the viscosity of the polymer emulsion and the polyurethane-coated sustained-release capsule polymer. Dilute 1mL of the polymer emulsion and the polyurethane-coated sustained-release capsule polymer to 100mL with water, stir evenly in a water bath at a certain temperature and 500r / min, and measure the viscosity of the aqueous solution at regular intervals.

[0038] The viscosity variation curves of SO4, SO6, SO8 and SO10 at 65℃ and 500rpm over time are shown in Figure 3 As can be seen from the figure, the delayed release time of sample SO8 is the longest, which is 27h, the release time of SO10 is similar to that of SO8, which is 26h, and the release time of SO6 and SO4 is 20h and 16h respectively. Therefore, SO8 has the best slow-release performance.

[0039] Effect of different temperatures on SO8 viscosity enhancement performance Figure 4 As shown in the figure, it can be seen that as the temperature increases, the viscosity increase rate of SO8 accelerates.

[0040] Figure 5 The SEM images of SO4, SO6, SO8, and SO10 are shown below. The capsule polymer is a spherical particle, most of which are large-sized particles, and there are also a small number of small-sized particles. Large-sized particles are more independent and have fewer connections between particles; while small-sized particles are easy to aggregate due to their high surface energy, and mostly exist in the form of inter-capsule bonding.

[0041] Figure 6 The particle size distribution curves of P(AM AA), SO4, SO6, SO8, and SO10 are shown in Figure 2. The particle size increases due to the formation of the shell. The particle size distribution of the capsule polymer is narrow and bimodal.

[0042] Figure 7 The viscosity change curve of SO8, BDO4 and BDO8 at 65℃ and 500rpm is as a function of time. It can be found that SO8 has the best anti-shear performance.

Claims

1. A method for preparing a polyurethane-coated sustained-release capsule polymer, characterized in that: Here are the steps: S1: adding the polyurethane prepolymer to the base oil, stirring at 20-30°C and 800-1200 r / min until the mixture is uniformly dispersed, to obtain a base oil solution of the polyurethane prepolymer; S2: Add the emulsifier to deionized water, and then add it to the base oil solution of the polyurethane prepolymer in S1, and stir for 0.5 h at 20-30° C. and 800-1200 r / min to form a uniform and stable mixed emulsion 1; S3: Add the polymer emulsion to the mixed emulsion 1 of S2, and stir for 0.5 h at 20-30°C and 800-1200 r / min to form a uniform and stable mixed emulsion 2; S4: Add polyol aqueous solution to the mixed emulsion 2 of S3, stir and react for 4-5 hours at 40-50° C. and 800-1200 r / min to obtain a polyurethane-coated sustained-release capsule polymer.

2. The preparation method according to claim 1, characterized in that: In step S1, the ratio of the mass of the polyurethane prepolymer to the mass of the base oil is 0.5-1:

1.

3. The preparation method according to claim 1, characterized in that: In step S2, the ratio of the mass of the emulsifier to the mass of the base oil in step S1 is 0.01-0.15:1, and the ratio of the mass of the deionized water to the mass of the base oil in step S1 is 1:0.5-1.

5.

4. The preparation method according to claim 1, characterized in that: In step S3, the ratio of the mass of the polymer emulsion to the mass of the mixed emulsion 1 is 1:3.6-4.

5. The preparation method according to claim 1, characterized in that: In step S4, the ratio of the mass of the polyol aqueous solution to the mass of the mixed emulsion 2 is 1:180-200.

6. The preparation method according to claim 1, characterized in that: The prepolymer monomers of the polyurethane prepolymer are isophorone diisocyanate and polyethylene glycol; the base oil is any one or more of white oil, kerosene, and liquid paraffin; the emulsifier is any one or more of MOA-9, MOA-3, Span80, Span85, Tween80, Tween60, and OP-10; the comonomer of the polymer is any one or more of acrylamide, 2-acrylamide-2-methylpropane sulfonic acid, acrylic acid, styrene sulfonic acid, and N-alkyl maleimide; and the polyol is any one or more of D-sorbitol and L-sorbitol.

7. A polyurethane-coated sustained-release capsule polymer, characterized in that: Prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the sustained-release capsule polymer as claimed in claim 7 in oil displacement.

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