Microfoam preparation device, preparation method, prepared microfoam and application thereof

Abstract

The present invention provides a microfoam preparation device, preparation method, prepared microfoam, and applications thereof. The preparation device includes: a container for loading a foaming liquid; a stirring device for stirring the foaming liquid in the container; and a homogenizing device for homogenizing the stirred foaming liquid. The stirring device is capable of providing a rotational speed of 400 to 1000 rpm, and the homogenizing device is a homogenizer. Compared to using a specific and complex microfoam generating device, the preparation device provided by the present invention has a simple structure, does not require high-speed stirring, and can effectively improve the controllability of the microfoam density.

Description

Technical Field

[0001] The present invention relates to the technical field of microfoam preparation, and in particular to a microfoam preparation device, a preparation method, the prepared microfoam and applications thereof. Background Art

[0002] After development, mature oil fields generally face the challenges of high water content, rapid injection pressure drops, insufficient energy, and rapidly declining production. After water injection, approximately two-thirds of the crude oil remains in the reservoir. Due to capillary forces, it is difficult to displace this oil simply by increasing the pressure differential. In theory, enhanced oil recovery is determined by both the sweep coefficient and the displacement efficiency. The mechanism involves expanding the sweep coefficient and improving the displacement efficiency. Foam systems have mobility adjustment and plugging effects, expanding the sweep coefficient and improving the displacement efficiency through profile control and flow diversion. Furthermore, the foaming agent in the foam system acts as a surfactant, reducing interfacial tension, emulsifying, and modifying wettability, thereby improving both oil washing and displacement efficiency. Foam flooding has become a widely used EOR method in oil and gas fields.

[0003] However, foam flooding still has some problems, such as poor stability, short validity period, easy adsorption of surfactants, and difficulty in injection.

[0004] Microfoam, also known as colloidal gas aphron (CGA), was first proposed by Sebba. It features a "one core, two layers, and three membranes" structure, with diameters typically ranging from 10 to 100 μm. Ahmadi used natural and commercial surfactants to prepare various colloidal gas foams. The total volume of the fluid remained stable for 72 hours, demonstrating superior stability compared to traditional foams. Telmadarreie prepared microfoam using nonylphenol polyoxyethylene ether and xanthan gum. Microscopic models demonstrated that the microfoam exhibited excellent plugging and profile control properties. Sand filling experiments also demonstrated that the injection pressure of the microfoam was only one-fifth that of the base fluid, demonstrating excellent injection performance.

[0005] The above research results show that microfoam plays a certain role in improving the stability and injectability of ordinary foam flooding. Foam miniaturization, that is, microfoam, has received more and more attention. At present, the application of microfoam systems is mainly concentrated in the separation and purification of metals and impurities, and the recovery and extraction of enzymes and proteins. In the field of oilfield chemistry, it is also mainly concentrated in drilling fluids, workover fluids, fracturing fluids, etc., such as patents CN104312550A, CN 102453471B, CN 102485828B, etc. There are few reports on the application of microfoam in oil displacement. On the other hand, the preparation of microbubbles requires a specific microbubble generating device. For example, patent CN 112689533A uses a porous medium with continuous pores as a microbubble generating device; patent CN111841416A obtains a microbubble generating device by assembling components such as a dissolved air tube, a microbubble generator, and a jet integrator. The above methods for generating microbubbles require additional instruments and are complicated to operate. High-speed stirring is also a method for preparing microbubbles, but it often fails to produce microbubbles with controllable gas content and density. Usually, the obtained microbubbles have high gas content and low density. Summary of the Invention

[0006] In view of the above-mentioned problems existing in the prior art, one of the objects of the present invention is to provide a microfoam preparation device, which, through the combined use of a specific stirring device and a homogenizing device, can avoid the use of a complex microfoam generating device and obtain microfoam with controllable air content and density.

[0007] The second object of the present invention is to provide a method for preparing microfoam corresponding to the first object, which obtains microfoam with controllable gas content and density without using a microfoam generating device with a complex structure.

[0008] A third object of the present invention is to provide a microfoam corresponding to the above-mentioned object.

[0009] A fourth object of the present invention is to provide an application of microfoam corresponding to the above-mentioned object.

[0010] To achieve one of the above purposes, the technical solution adopted by the present invention is as follows:

[0011] A microfoam preparation device comprising:

[0012] a container for containing the foaming liquid;

[0013] a stirring device for stirring the foaming liquid in the container;

[0014] A homogenizing device is used to homogenize the foaming liquid after stirring.

[0015] Wherein, the stirring device is a stirring device capable of providing a rotation speed of 400 to 1000 rpm, and the homogenizing device is a homogenizer.

[0016] According to the present invention, the shape and size of the container are not particularly limited, and those skilled in the art can select them according to actual ingredient requirements. In some preferred embodiments of the present invention, the container has a cylindrical structure, and the container diameter is no greater than 2.5 times the impeller blade diameter. Preferably, the container diameter is 1 to 2.5 times the impeller blade diameter, and more preferably 1.05 to 2.5 times the impeller blade diameter.

[0017] According to the present invention, the depth of the container is not limited, as long as its depth is not less than 1.8 times the liquid level of the injected foaming liquid during use.

[0018] In some preferred embodiments of the present invention, the homogenizer is a homogenizer capable of providing a rotation speed of 4000 to 10000 rpm.

[0019] In some preferred embodiments of the present invention, the homogenizer is a homogenizer capable of providing a rotation speed of 4000 to 7500 rpm.

[0020] In some specific embodiments of the present invention, the model of the homogenizer may be IKA T25, FLUKO FA25 or POLYTRON PT6100D.

[0021] In some preferred embodiments of the present invention, the impeller used in the stirring device is a propeller impeller or a frame impeller.

[0022] According to the present invention, the connection method of the container, stirring device and homogenizing device is not particularly limited, as long as the stirring device can stir the foaming liquid in the container and the homogenizing device can homogenize the foaming liquid in the container.

[0023] To achieve the second of the above objectives, the technical solutions adopted by the present invention are as follows:

[0024] A method for preparing microfoam, comprising:

[0025] S1. The foaming liquid is stirred to obtain a preparatory liquid;

[0026] S2. homogenize the preparatory solution to obtain microfoam,

[0027] Wherein, in step S1, the stirring treatment conditions include: a stirring speed of 400 to 1000 rpm and a stirring time of 0.5 to 3 hours; and

[0028] In step S2, the homogenization process is performed in a homogenizer.

[0029] In some preferred embodiments of the present invention, in step S2, the homogenization treatment conditions include: a treatment time of 3 to 15 minutes; and controlling the operating parameters of the homogenizer to have a rotation speed of 4000 to 10000 rpm.

[0030] In some preferred embodiments of the present invention, in step S1, the foaming liquid comprises the following components in parts by weight:

[0031] 0.1-1 part of foaming agent;

[0032] 0.1-1 part of foam stabilizer;

[0033] 100 parts water,

[0034] The foaming agent is selected from at least one of a betaine surfactant and an anionic surfactant, and the foam stabilizer is selected from at least one of a biopolymer and a synthetic polymer.

[0035] In some preferred embodiments of the present invention, the betaine surfactant is selected from at least one of an alkyl betaine having an alkyl carbon number of 8-22 and an alkyl amide betaine having an alkyl carbon number of 8-22.

[0036] According to the present invention, the betaine surfactant is selected from at least one of dodecyl dimethyl betaine, tetradecyl dimethyl betaine, octadecyl dimethyl betaine, dodecyl dihydroxyethyl betaine, lauryl amidopropyl betaine, cocamidopropyl betaine and octadecyl amidopropyl betaine.

[0037] In some preferred embodiments of the present invention, the anionic surfactant is selected from at least one of a sulfonate surfactant and a sulfate surfactant.

[0038] According to the present invention, the anionic surfactant is at least one selected from sodium dodecylbenzenesulfonate, α-olefin sulfonate and sodium lauryl sulfate.

[0039] According to the present invention, the α-olefin sulfonate is C8-C 18 α-olefin sulfonate, preferably C 14 -C 16 α-Alkenyl sulfonate.

[0040] In some preferred embodiments of the present invention, the biopolymer is selected from at least one of starch, xanthan gum, guar gum and carboxymethyl cellulose, and the synthetic polymer is selected from partially hydrolyzed polyacrylamide.

[0041] In some preferred embodiments of the present invention, the degree of hydrolysis of the partially hydrolyzed polyacrylamide is 10% to 40%.

[0042] In some preferred embodiments of the present invention, the density of the microfoam is adjusted by changing the stirring speed and / or stirring time.

[0043] In some preferred embodiments of the present invention, the density of the microfoam is reduced by increasing the stirring speed and / or increasing the stirring time.

[0044] According to the present invention, the stirring process can introduce a gas phase such as air into the foaming liquid, so by changing the stirring parameters such as speed and time, the morphology of the micro foam finally formed, such as density, can be affected.

[0045] In some preferred embodiments of the present invention, the preparation method described in any one of the above embodiments is carried out in the preparation device described in any one of the above embodiments.

[0046] According to the present invention, the method for preparing the foaming liquid comprises:

[0047] (1) mixing a foam stabilizer and water to obtain a base liquid, for example, slowly adding the foam stabilizer to water under stirring and thoroughly mixing to obtain the base liquid;

[0048] (2) Add a required amount of foaming agent to the base liquid to obtain a foaming liquid.

[0049] According to the present invention, in step (1), the stirring conditions include: a stirring speed of 300 to 700 rpm and a stirring time of 1 to 4 hours.

[0050] To achieve the third of the above objectives, the technical solutions adopted by the present invention are as follows:

[0051] A microfoam prepared by the preparation method described in any one of the above embodiments, having a density of 0.5 to 0.95 g / cm 3 , the average diameter is not greater than 100 μm, preferably 50 μm to 95 μm.

[0052] To achieve the fourth objective above, the present invention adopts the following technical solutions:

[0053] An application of the microfoam according to any one of the above embodiments in the field of oil extraction, preferably in the field of oil displacement, more preferably as an oil displacement agent.

[0054] In the present invention, the term "microfoam" refers to foam with an average diameter of 10 to 100 μm.

[0055] The preparation method of microfoam provided by the present invention does not require a specific foam generating device, and foaming is carried out under low-speed stirring. The foaming agent can reduce the surface tension of gas and liquid, and the gas slowly enters the bulk phase through the action of low-speed mechanical stirring. The foam stabilizer and the foaming agent synergistically arrange in order on the surface of the gas core to form a dense outer protective layer of the gas core, which effectively prevents the escape of gas in the gas core, keeps the gas core stable, and improves the strength of the microbubble. The obtained bubbles are spherical, independently dispersed or in point-to-point contact in the liquid, and the liquid film is relatively thick. By adjusting the stirring rate and stirring time, the gas content is controlled, and a microbubble system with controllable density can be obtained, which is suitable for tertiary oil recovery in oil fields. Compared with the difficult-to-control method of the traditional high-speed stirring preparation method in which the inflation rate is too fast and the inflation volume is too large, the controllability of the microfoam density can be effectively improved, and microbubble systems with different gas contents and densities can be prepared according to different needs.

[0056] In short, the beneficial effects of the present invention are at least in the following aspects:

[0057] First, the device and method provided by the present invention do not require a special microbubble generating device during the preparation process, nor do they require foaming under high-speed stirring, thus overcoming the defects of uncontrollable gas content and density under high stirring.

[0058] Secondly, the density of the micro foam produced by the device and method provided by the present invention is 0.5 to 0.95 g / cm 3 The spacing is controllable and the average diameter is no more than 100μm. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a microscope photograph of the microfoam formed in Example 1. DETAILED DESCRIPTION

[0060] The present invention is described in detail below through examples, but the protection scope of the present invention is not limited to the following description.

[0061] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents or instruments used, if the manufacturer is not specified, are conventional products that can be obtained through commercial channels.

[0062] In the following embodiments, unless otherwise specified, the impeller used in the stirring device is a frame-type impeller.

[0063] In the following embodiments, unless otherwise specified, the model of the homogenizer used is IKA T25.

[0064] In the following embodiments, unless otherwise specified, the diameter of the prepared microfoam was measured by microscopic observation, and the density of the microfoam was measured by a liquid densitometer.

[0065] Example 1

[0066] In terms of mass percentage, 0.5 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.32 parts of dodecyl dihydroxyethyl betaine and 0.08 parts of sodium lauryl sulfate were added to obtain a foaming liquid. The speed was adjusted to 700 rpm and stirred for 30 minutes. After that, the mixture was dispersed in a homogenizer at a speed of 5500 rpm for 8 minutes to obtain a milky white and uniformly dispersed micro-foam oil-displacing agent.

[0067] The average diameter of bubbles in the microfoam oil displacement agent is 72 μm and the density is 0.85 g / cm 3 .

[0068] Example 2

[0069] In terms of mass percentage, 0.5 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.32 parts of dodecyl dihydroxyethyl betaine and 0.08 parts of sodium lauryl sulfate were added to obtain a foaming liquid. The speed was adjusted to 900 rpm and stirred for 1 hour. After that, the mixture was dispersed in a homogenizer at a speed of 5500 rpm for 8 minutes to obtain a milky white and uniformly dispersed micro-foam oil-displacing agent.

[0070] The average diameter of bubbles in the microfoam oil displacement agent is 68 μm and the density is 0.67 g / cm 3 .

[0071] Example 3

[0072] In terms of mass percentage, 0.5 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.32 parts of dodecyl dihydroxyethyl betaine and 0.08 parts of sodium lauryl sulfate were added to obtain a foaming liquid. The speed was adjusted to 400 rpm and stirred for 3 hours. After that, the mixture was dispersed in a homogenizer at a speed of 5500 rpm for 8 minutes to obtain a milky white and uniformly dispersed micro-foam oil-displacing agent.

[0073] The average diameter of bubbles in the microfoam oil displacement agent is 77 μm and the density is 0.9 g / cm 3 .

[0074] Example 4

[0075] In terms of mass percentage, 0.5 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.32 parts of dodecyl dihydroxyethyl betaine and 0.08 parts of sodium lauryl sulfate were added to obtain a foaming liquid. The speed was adjusted to 1000 rpm and stirred for 2 hours. After that, the mixture was dispersed in a homogenizer at a speed of 5500 rpm for 8 minutes to obtain a milky white and uniformly dispersed micro-foam oil-displacing agent.

[0076] The average diameter of bubbles in the microfoam oil displacement agent is 70 μm and the density is 0.59 g / cm 3 .

[0077] Example 5

[0078] The only difference between this embodiment and embodiment 1 is that the composition of the foaming liquid is: 0.6 parts of polyacrylamide with a hydrolysis degree of 35%, 0.3 parts of cocamidopropyl betaine, 0.1 parts of sodium dodecylbenzenesulfonate and 100 parts of water.

[0079] The average diameter of bubbles in the prepared microfoam oil displacement agent was measured to be 75 μm, and the density was 0.83 g / cm 3 .

[0080] Example 6

[0081] In terms of mass percentage, 0.4 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.2 parts of dodecyl dimethyl betaine and 0.1 parts of sodium dodecylbenzene sulfonate were added to obtain a foaming liquid. The speed was adjusted to 700 rpm and stirred for 1 hour. After that, the mixture was dispersed in a homogenizer at 4000 rpm for 8 minutes to obtain a milky white and uniformly dispersed micro-foam oil-displacing agent.

[0082] The average diameter of bubbles in the microfoam oil displacement agent is 80 μm and the density is 0.78 g / cm 3 .

[0083] Example 7

[0084] In terms of mass percentage, 0.4 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.2 parts of dodecyl dimethyl betaine and 0.1 parts of sodium dodecylbenzene sulfonate were added to obtain a foaming liquid. The speed was adjusted to 700 rpm and stirred for 1 hour. After that, the mixture was dispersed in a homogenizer at 7000 rpm for 8 minutes to obtain a milky white and uniformly dispersed micro-foam oil-displacing agent.

[0085] The average diameter of bubbles in the microfoam oil displacement agent is 66 μm and the density is 0.78 g / cm 3 .

[0086] Comparative Example 1

[0087] In terms of mass percentage, 0.5 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.32 parts of dodecyl dihydroxyethyl betaine and 0.08 parts of sodium lauryl sulfate were added to obtain a foaming liquid; the mixture was stirred at a high speed of 3000 rpm for 3 minutes to obtain a milky white dispersion.

[0088] The average diameter of the bubbles in the milky white dispersion was measured to be 75 μm, and the density was 0.29 g / cm 3 .

[0089] Comparative Example 2

[0090] In terms of mass percentage, 0.5 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.32 parts of dodecyl dihydroxyethyl betaine and 0.08 parts of sodium lauryl sulfate were added to obtain a foaming liquid. The speed was adjusted to 700 rpm and stirred for 30 minutes to obtain a milky white dispersion.

[0091] The average diameter of the bubbles in the milky white dispersion was measured to be 142 μm, and the density was 0.85 g / cm 3 .

[0092] Comparative Example 3

[0093] In terms of mass percentage, 0.5 parts of xanthan gum were slowly added to 100 parts of water under stirring at 500 rpm. After stirring for 2 hours, 0.32 parts of dodecyl dihydroxyethyl betaine and 0.08 parts of sodium lauryl sulfate were added to obtain a foaming liquid. The speed was adjusted to 700 rpm and stirred for 30 minutes. After that, an ultrasonic dispersing device was used to disperse the mixture at a power of 350 W for 15 minutes to obtain a milky white dispersion.

[0094] The average diameter of the bubbles in the milky white dispersion was measured to be 140 μm, and the density was 0.85 g / cm 3 .

[0095] The above examples 1 to 7 illustrate that the microfoam oil displacement agent preparation method of the present invention can control the gas content of the system by adopting different stirring speeds or stirring times, and the density of the microfoam oil displacement agent is between 0.5 and 0.95 g / cm 3 The foam diameter of the prepared foam is below 100 μm, and has the typical structural characteristics of "one core, two layers and three membranes", which belongs to microfoam (colloidal gas foam). Comparative Example 1 adopts the preparation method of high-speed stirring, and the density of the obtained foam system is relatively small and uncontrollable. Comparative Example 2 only uses low-speed stirring and is inhomogeneous, and the foam diameter of the obtained foam system is relatively large, which does not belong to microfoam. It can be seen that the preparation method adopted by the present invention can not only control the system density but also obtain foam of smaller size, that is, a microfoam oil-displacing agent with controllable density can be obtained.

[0096] Test Example 1

[0097] The microfoam oil displacement agent prepared in Example 2 was subjected to a physical simulation displacement experiment. The core used for displacement had a diameter of 2.5 cm, a length of 20 cm, and a permeability of 2.5 μm. 2First, water drive was performed to a water content of 98%. After the water drive was completed, 1pv (core pore volume) of the above-mentioned micro-foam oil displacement agent was injected, and then water drive was performed to a water content of 98%. The results showed that the crude oil recovery rate could be increased by 16% based on water drive.

[0098] It should be noted that the embodiments described above are only used to explain the present invention and do not constitute any limitation of the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory words, rather than restrictive words. The present invention may be modified as specified within the scope of the claims of the present invention, and the present invention may be revised without departing from the scope and spirit of the present invention. Although the present invention described therein relates to specific methods, materials and embodiments, it does not mean that the present invention is limited to the specific examples disclosed therein. On the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for preparing microfoam, comprising: S1. The foaming liquid is stirred to obtain a preparatory liquid; S2. The preparatory solution is homogenized to obtain microfoam, Wherein, in step S1, the stirring treatment conditions include: a stirring speed of 400-1000 rpm and a stirring time of 0.5-3 h; and In step S2, the homogenization process is performed in a homogenizer; the operating parameters of the homogenizer are controlled as follows: the speed is 4000-10000 rpm; In step S1, the foaming liquid includes the following components in parts by weight: 0.1~1 part of foaming agent; 0.1~1 part of foam stabilizer; 100 parts water, Wherein, the foaming agent is selected from at least one of betaine surfactants and anionic surfactants, and the foam stabilizer is selected from at least one of biopolymers and synthetic polymers; The density of the microfoam can be reduced by increasing the stirring speed and / or the stirring time.

2. The preparation method according to claim 1, characterized in that The homogenization treatment conditions include: the treatment time is 3 to 15 minutes.

3. The preparation method according to claim 1, characterized in that The betaine surfactant is selected from at least one of an alkyl betaine having an alkyl carbon number of 8-22 and an alkylamide betaine having an alkyl carbon number of 8-22; and / or the anionic surfactant is selected from at least one of a sulfonate surfactant and a sulfate surfactant; and / or the biopolymer is selected from at least one of starch, xanthan gum, guar gum and carboxymethyl cellulose, and the synthetic polymer is selected from partially hydrolyzed polyacrylamide.

4. The preparation method according to claim 3, characterized in that The degree of hydrolysis of the partially hydrolyzed polyacrylamide is 10% to 40%.

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