In-situ forming system and method for subject and object films and application of in-situ forming system and method

Abstract

The invention discloses a subject-guest film in-situ forming system and method and application thereof.The subject-guest film in-situ forming system comprises a hydrophilic layer, a hydrophobic layer and a subject-guest characteristic film located between the hydrophilic layer and the hydrophobic layer, the hydrophilic layer is provided with a hydrophilic film, water-based functional liquid and water-based functional molecules, and the hydrophobic layer is provided with a hydrophobic film, a water-based functional liquid and a water-based functional molecule. The hydrophilic film is soaked in the water-based functional liquid; the hydrophobic layer is provided with a hydrophobic membrane, hydrophobic functional liquid and hydrophobic functional molecules, and the hydrophobic membrane is soaked in the hydrophobic functional liquid; the hydrophilic functional molecules and the hydrophobic functional molecules form the host-guest characteristic film with certain mechanical strength and stability on an interface between the hydrophilic film and the hydrophobic film through host-guest interaction and hydrogen-bond interaction. The system can be used for improving the recovery rate of crude oil.

Description

Technical Field

[0001] The present invention relates to a system and method for in-situ formation of host-guest thin films, which can be used for gas separation, oil displacement, etc. It belongs to the new in-situ membrane synthesis technology. Background Art

[0002] Actual reservoir geological conditions are complex and variable, with conditions such as variable temperature, pressure, pore size and shape. The in-situ membrane preparation method can instantaneously adjust the properties of the membrane, such as porosity, permeability and strength, according to the formation conditions to adapt to different geological environments. In-situ film formation according to the characteristics of the pores to be blocked can achieve more precise plugging, reduce interference with non-target areas, and improve the plugging efficiency. Traditional membrane materials may require complex pretreatment and transportation processes. Summary of the Invention

[0003] Aiming at the disadvantages of high requirements for preparation conditions, complex equipment and cumbersome operation of the existing film formation technology, the present invention has developed a system and method with simple operation for in-situ formation of host-guest characteristic thin films with stability, mechanical strength and no pollution.

[0004] One of the technical solutions provided by the present invention is:

[0005] A system for in-situ formation of host-guest thin films includes a hydrophilic layer, a hydrophobic layer and a host-guest characteristic thin film located between the hydrophilic layer and the hydrophobic layer. Among them, the hydrophilic layer has a hydrophilic membrane, a water-based functional liquid and water-based functional molecules, and the hydrophilic membrane is impregnated in the water-based functional liquid; the hydrophobic layer has a hydrophobic membrane, a hydrophobic functional liquid and hydrophobic functional molecules, and the hydrophobic membrane is impregnated in the hydrophobic functional liquid; the hydrophilic functional molecules and the hydrophobic functional molecules form the host-guest characteristic thin film with a certain mechanical strength and stability through hydrogen bonding at the interface between the hydrophilic membrane and the hydrophobic membrane.

[0006] The present invention also provides the application of the above-mentioned system for in-situ formation of host-guest thin films in oil recovery.

[0007] Another technical solution provided by the present invention is:

[0008] A host-guest hydrogen bond liquid gating system includes a liquid-based composite porous membrane unit, a gating host, and a gas channel; the liquid-based composite porous membrane unit includes a hydrophilic layer, a hydrophobic layer, and a host-guest characteristic thin film located between the hydrophilic layer and the hydrophobic layer. Among them, the hydrophilic layer has a hydrophilic membrane, a water-based functional liquid, and water-based functional molecules, and the hydrophilic membrane is impregnated in the water-based functional liquid; the hydrophobic layer has a hydrophobic membrane, a hydrophobic functional liquid, and hydrophobic functional molecules, and the hydrophobic membrane is impregnated in the hydrophobic functional liquid; the hydrophilic functional molecules and the hydrophobic functional molecules form the host-guest characteristic thin film with a certain mechanical strength and stability through hydrogen bonding at the interface between the hydrophilic membrane and the hydrophobic membrane; the liquid-based composite porous membrane unit is located in the gating host, and a gas input channel and a gas output channel are respectively arranged on both sides of the liquid-based composite porous membrane unit, and the gas input channel and the gas output channel constitute the gas channel.

[0009] Further, the gating host includes two clamping members and a sealing material; the sealing material cooperates with the two clamping members at the connection to achieve a sealing effect.

[0010] Another technical solution provided by the present invention is:

[0011] A method for in-situ forming a host-guest thin film includes the following steps:

[0012] Step 1, select a water-based functional liquid and a hydrophobic-based functional liquid, as well as a hydrophilic membrane and a hydrophobic membrane that can be at least partially wetted.

[0013] Step 2, impregnate the hydrophilic membrane in the water-based functional liquid, impregnate the hydrophobic membrane in the hydrophobic-based functional liquid, then stack the two membranes and place them in the gating host.

[0014] Step 3, the hydrophilic functional molecules in the water-based functional liquid and the hydrophobic functional molecules in the hydrophobic-based functional liquid form the host-guest characteristic thin film with a certain mechanical strength and stability through hydrogen bonding at the interface between the hydrophilic membrane and the hydrophobic membrane; after the transmembrane pressure of the host-guest thin film is stable, the host-guest thin film is obtained.

[0015] Further, in step 3, the stabilization time is at least 2 h. For example, 2 h - 24 h. More preferably 2 h - 5 h.

[0016] Further, the hydrophilic membrane includes at least one of a nylon membrane, a mixed cellulose membrane, a copper mesh, and a polyvinyl alcohol membrane; the hydrophobic membrane includes at least one of a polyvinylidene fluoride membrane and a polytetrafluoroethylene membrane.

[0017] Further, the average pore size range of the hydrophilic membrane or the hydrophobic membrane is 1 - 10 μm.

[0018] Optionally, the functional liquid can at least partially wet the porous membrane.

[0019] The present invention can also provide membranes with different wettability / aperture characteristics. The preparation method is to immerse hydrophilic membranes with different pore sizes in an aqueous functional solution with a certain concentration, and hydrophobic membranes with different pore sizes in a hydrophobic functional liquid. After a period of time, hydrophilic functional molecules and hydrophobic functional molecules will form a skin-like characteristic membrane at the interface of the porous membranes with different wettabilities through hydrogen bonding. This membrane has stability and a certain mechanical strength.

[0020] Optionally, the aqueous functional solution includes but is not limited to water, α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin aqueous solution; the oil-based functional liquid includes but is not limited to crude oil, alkanes, silicone oil, perfluoroalkanes, aromatic hydrocarbons, etc.

[0021] Optionally, the flowing gas in the gas channel includes but is not limited to air, and the flow rate range is: 0.1 mL / min - 5 mL / min.

[0022] The present invention provides a host-guest thin film in-situ formation system and method. By using functional membranes with different wettabilities, functional molecules with host-guest behavior can spontaneously form a skin-like thin film in-situ at the two-phase interface. The thin film formed in-situ by this method has stability and a certain mechanical strength, and can resist a certain external pressure. It can be used in crude oil displacement, so it has important application value in oil exploitation. Moreover, the present invention is an in-situ preparation membrane method, which can be directly prepared downhole or in the reservoir, reducing the transportation and processing costs of materials, and can better adapt to the temperature and pressure changes in the reservoir, reducing the decline or damage of membrane performance caused by environmental changes. By forming a membrane in specific pores, the fluid can be forced to pass through small pores, which are usually associated with higher permeability, thereby improving the recovery rate of crude oil, and having higher operation flexibility and controllability. The chemical materials used in the in-situ preparation membrane method can react directly in the reservoir, reducing the use and storage of chemical materials on the ground and reducing the risk of environmental pollution.

[0023] The beneficial effects of the present invention are as follows:

[0024] 1. The present invention relates to the in-situ generation technology of membranes. Compared with traditional membrane synthesis technologies, the synthesis process is simple, and the formed host-guest characteristic membrane has stability and a certain mechanical strength.

[0025] 2. It is possible to regulate the mechanical strength of the host-guest characteristic membrane by changing the pore size of the functional membranes with different wettabilities.

[0026] 3. According to different requirements, hydrophilic and hydrophobic functional molecules and membranes with different wettabilities can be selected, with wide applicability.

[0027] 4. It has good crude oil displacement efficiency. Description of the Drawings

[0028] Figure 1 This is the diagram of the host-guest thin film forming device of the present invention;

[0029] Figure 2 This is the mechanism diagram of the generated thin film of the present invention;

[0030] Figure 3 This is the pressure transformation of the composite polytetrafluoroethylene-nylon membrane system with different initial pore sizes in Example 2;

[0031] Figure 4 This is the microscopic characterization of the film morphology prepared from different aqueous phases in Example 3;

[0032] Figure 5 This is the comparison of the transmembrane pressure change of the composite membrane system before and after 2 hours under different gas flow rates in Example 4

[0033] Figure 6 This is the film morphology formed under different concentrations of β-cyclodextrin aqueous solution in Example 5;

[0034] Figure 7 This is the test comparison of the oil displacement effect of crude oils from different regions in Example 6;

[0035] Figure 8 This is the test of the oil displacement efficiency of different aqueous phase systems in Example 7. Detailed implementation manners

[0036] The following further explains the present invention in conjunction with the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] The device for using the in-situ host-guest thin film forming system is as shown in the appendix Figure 1As shown in the figure. The device of the present invention includes a liquid-based composite porous membrane unit 1, a gating body 5, a gas input channel 6, and a gas output channel 7. The liquid-based composite porous membrane unit 1 includes a hydrophilic solution layer 2, a host-guest characteristic thin film 3, and a hydrophobic organic layer 4. The hydrophilic layer 2 is composed of a hydrophilic membrane 21, an aqueous functional solution 22, and aqueous functional molecules 23. The hydrophilic membrane 21 is impregnated in the aqueous functional solution 22; the hydrophobic layer 4 is composed of a hydrophobic membrane 41, an oil-based functional liquid 42, and oil-based functional molecules 43. The hydrophobic membrane 41 is impregnated in the oil-based functional liquid 42. The gating body 5 includes a clamping member 51, a clamping member 53, and a sealing material 52. The liquid-based composite porous membrane unit 1 is located between the clamping member 51 and the clamping member 53; the sealing material 52 cooperates with the clamping member 51 and the clamping member 53 at the connection to achieve a sealing effect. The gas input channel 6 and the gas output channel 7 are respectively located on opposite sides of the gating body 5 and are connected to form a gas flow channel. A gas with a certain pressure (the pressure is slightly lower than the critical pressure of the gas passing through the host-guest thin film) enters through the gas input channel 6 and leaves the system through the gas output channel 7. The formation and mechanical strength of the characteristic film are reflected by testing the transmembrane pressure.

[0039] As Figure 2 shown in the mechanism, the aqueous functional molecules 23 in the hydrophilic layer and the oil-based functional molecules 43 in the hydrophobic layer form a host-guest complex through hydrogen bonding, and a skin-like thin film is formed synergistically at the oil-water interface. As the gas continuously enters the system, the pressure on the thin film gradually increases. When the pressure exerted by the gas on the host-guest characteristic thin film 3 is lower than the critical transmembrane pressure of the thin film, the thin film will not break and remains in its original state. When the pressure on the host-guest characteristic thin film 3 is greater than its critical pressure, it will break, the gas transport channel will communicate with the atmosphere, and the pressure inside the system will gradually decrease and finally be consistent with the atmospheric pressure. Thin films with different mechanical strengths have different critical transmembrane pressures. Detecting the pressure mutation point at which the thin film is damaged by the gas can be used to characterize the mechanical strength of the formed thin film.

[0040] Example 2

[0041] Polytetrafluoroethylene-nylon membrane systems with different pore sizes were selected to detect the influence of pore size on the system pressure. Based on the in-situ generation device of the host-guest thin film shown in Figure 1 the figure, the aqueous functional solution was selected for the hydrophilic layer 2, and 22 was a 0.005M aqueous solution of β-cyclodextrin (the aqueous functional molecules 23 were β-cyclodextrin), and nylon membranes 21 with different pore sizes (pore sizes of 1μm, 5μm, and 8μm) were infiltrated; dodecane was selected as the oil-based functional molecules 43 for the hydrophobic layer 4, and a polytetrafluoroethylene membrane 41 with a fixed pore size (pore size of 1μm) was infiltrated. The hydrophilic layer, the hydrophobic layer, and the in-situ formed host-guest characteristic thin film 3 formed the liquid-based composite porous membrane unit 1. As Figure 3 shown in the figure, the transmembrane pressure of the system decreases with the increase of the pore size of the nylon membrane.

[0042] The polytetrafluoroethylene membrane with an average pore size of 5 μm was selected and the same transmembrane pressure test as above was carried out with nylon membranes 21 with different pore sizes (pore sizes of 1 μm, 5 μm, and 8 μm). As Figure 3 shown, the difference in the transmembrane pressure of the system and the polytetrafluoroethylene membrane 41 with a fixed pore size of 1 μm is not significant, indicating that the nylon membrane 21 and its compatible aqueous solution 22 play a dominant role in the transmembrane pressure of the system.

[0043] Example 3

[0044] Select the in-situ formation method of host-guest characteristic membranes with different mechanical strengths of different water-based functional molecules. Refer to Figure 2 the schematic diagram of the in-situ host-guest thin film generation system shown. Water, α-cyclodextrin solution, β-cyclodextrin solution, and γ-cyclodextrin solution with a concentration of 0.004 M were selected as the aqueous solution 22, and the nylon membrane 21 with an average pore size of 5 μm was infiltrated respectively; dodecane was selected as the oil-based liquid 42 to infiltrate the polytetrafluoroethylene membrane 41 with an average pore size of 5 μm. The nylon membrane and the polytetrafluoroethylene membrane were laminated, and after a period of time, the host-guest characteristic thin film 3 was formed in-situ, and the surface morphology was characterized by scanning electron microscopy (SEM) before and after film formation. As Figure 4 shown, the morphology of the thin film formed by β-cyclodextrin is the clearest and most stable. This is because the binding energies of different cyclodextrins in the aqueous phase and the oil phase are different. The binding energy of β-cyclodextrin and dodecane is the lowest, the formed film is the most stable, and has better mechanical strength.

[0045] Example 4

[0046] Select different flow rates of the flowing gas and detect its influence on the transmembrane pressure of the host-guest characteristic thin film. Based on the host-guest thin film in-situ formation device shown in Figure 1 , the water-based functional solution 22 was selected as 0.004 M β-cyclodextrin aqueous solution to infiltrate the nylon membrane 21 with an average pore size of 5 μm, and the oil-based functional liquid 42 was selected as dodecane to infiltrate the polytetrafluoroethylene membrane 41 with an average pore size of 5 μm, together forming the liquid-based composite membrane unit 1. The flowing gas was air with a flow rate of 0.5 mL / min - 3 mL / min, and the transmembrane behavior at different gas flow rates was tested. As Figure 5 shown, as the flow rate of the introduced gas increases, the transmembrane pressure of the host-guest characteristic thin film 3 also gradually increases, indicating that the formed thin film has mechanical strength and can resist a certain external pressure.

[0047] After two hours, the same transmembrane pressure test was carried out again. As Figure 5 shown, the transmembrane pressure of the host-guest characteristic thin film 3 increases with the increase of the reaction time, indicating that the generated thin film is more stable.

[0048] Example 5

[0049] In-situ generation method of host-guest thin films with different concentrations of aqueous solutions. The hydrophilic layer 2 is a nylon membrane with an average pore size of 5 μm infiltrated with β-cyclodextrin aqueous solutions at different concentrations (0.001, 0.002, 0.003, and 0.005 M), and the hydrophobic layer 4 is a polytetrafluoroethylene membrane with an average pore size of 5 μm infiltrated with dodecane. The transport fluid is air. The impregnated nylon membrane and polytetrafluoroethylene membrane are stacked together, and β-cyclodextrin and dodecane will form host-guest complexes through hydrogen bonds at the oil-water interface to form a skin-like thin film 3. As Figure 3 shown, the thin film with a β-cyclodextrin aqueous solution concentration of 0.005 M is the most stable. As Figure 6 shown, after the formation of host-guest thin films with different morphological characteristics at the interface of the two thin films, the surface morphologies of the initial polytetrafluoroethylene membrane and nylon membrane have obvious changes, and a uniform covering substance different from the initial surface appears, proving the formation of the host-guest thin film.

[0050] Example 6

[0051] Oil displacement test of an in-situ generation system of host-guest thin films. A β-cyclodextrin solution with a concentration of 0.004 M is selected as the aqueous liquid 22 to infiltrate a nylon membrane 21 with an average pore size of 5 μm to form a hydrophilic solution layer 2; Middle East crude oil and North Third Area crude oil are selected to infiltrate a polytetrafluoroethylene membrane 41 with an average pore size of 5 μm. After a period of time, the two membranes are stacked, and the host-guest characteristic thin film 3 will be formed between the nylon membrane and the polytetrafluoroethylene membrane. At the same time, air is introduced into the system to test the transmembrane pressure. The difference in transmembrane pressure characterizes the mechanical strength of the characteristic film to a certain extent. After two hours, the transmembrane pressure is tested again. As Figure 7 shown, after 2 hours of reaction, the transmembrane pressures of Middle East and North Third Area crude oils have increased, proving that these two crude oils as the oil phase can form characteristic thin films at the oil-water interface in the host-guest-hydrogen bond system, and with the increase of reaction time, the formed host-guest characteristic thin film 3 is more stable and can achieve an effective displacement effect.

[0052] Example 7

[0053] Oil displacement efficiency test of an in-situ generation system of host-guest thin films. A β-cyclodextrin solution with a concentration of 0.004 M and deionized water are respectively selected as the aqueous functional liquid 22 and injected into a homogeneous Berea core with an air permeability of 30×10 -3 μm 2 (which has been vacuum-treated for 4 hours). When the cumulative injection volume reaches twice the pore volume, the injection of water or β-cyclodextrin solution is stopped. The injection rate is kept constant at 0.35 mL / min. Two injection methods are adopted: continuous injection of water or cyclodextrin solution; injection of cyclodextrin solution in an amount of half the pore volume (0.5 PV), then pausing for 2 hours and continuing the injection. As Figure 8As shown, the dynamic pressure and recovery rate during the displacement process were recorded. As the injection volume increased, the pressure first increased and then decreased. For the method of pausing for 2 hours after injecting half of the pore volume (0.5PV) of the cyclodextrin solution and then continuing the injection (the second method), the crude oil displacement efficiency reached 28.6 ± 0.10%, which was higher than that of continuous injection of water or cyclodextrin solution (the first method), indicating that a uniform thin film was formed after the reaction between the aqueous cyclodextrin solution and crude oil for 2 hours, showing a better displacement effect.

[0054] The above embodiments are only used to further illustrate a host-guest thin film in-situ formation system and method of the present invention. However, the present invention is not limited to the embodiments. Any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention all fall within the protection scope of the technical solution of the present invention.

Claims

1. A host-guest thin film in-situ formation system, characterized in that: The invention comprises a hydrophilic layer, a hydrophobic layer and a host-guest characteristic film located between the hydrophilic layer and the hydrophobic layer, wherein the hydrophilic layer comprises a hydrophilic film, a water-based functional liquid and a water-based functional molecule, and the hydrophilic film is immersed in the water-based functional liquid; the hydrophobic layer comprises a hydrophobic film, a hydrophobic functional liquid and a hydrophobic functional molecule, and the hydrophobic film is immersed in the hydrophobic functional liquid; the hydrophilic functional molecule and the hydrophobic functional molecule form the host-guest characteristic film having certain mechanical strength and stability at the interface between the hydrophilic film and the hydrophobic film through hydrogen bonding.

2. The host-guest thin film in-situ formation system according to claim 1, characterized in that: The hydrophilic membrane includes at least one of a nylon membrane, a mixed cellulose membrane, a copper mesh, and a polyvinyl alcohol membrane; the hydrophobic membrane includes at least one of a polyvinylidene fluoride membrane and a polytetrafluoroethylene membrane.

3. The host-guest thin film in-situ formation system according to claim 1, characterized in that: The water-based functional solution includes at least one of water, α-cyclodextrin, β-cyclodextrin or γ-cyclodextrin aqueous solution; the hydrophobic functional liquid includes at least one of crude oil, alkane, silicone oil, perfluoroalkane and aromatic hydrocarbon.

4. The host-guest thin film in-situ formation system according to claim 1, characterized in that: The average pore size of the hydrophilic membrane or the hydrophobic membrane is in the range of 1-10 μm.

5. Use of a host-guest thin film in-situ formation system as claimed in any one of claims 1 to 4 in oil recovery.

6. A host-guest hydrogen-bonded liquid gating system, characterized in that: It includes a liquid-based composite porous membrane unit, a gating body and a gas channel; the liquid-based composite porous membrane unit includes a hydrophilic layer, a hydrophobic layer and a host-guest characteristic film located between the hydrophilic layer and the hydrophobic layer, wherein the hydrophilic layer has a hydrophilic membrane, a water-based functional liquid and a water-based functional molecule, and the hydrophilic film is immersed in the water-based functional liquid; the hydrophobic layer has a hydrophobic membrane, a hydrophobic functional liquid and a hydrophobic functional molecule, and the hydrophobic membrane is immersed in the hydrophobic functional liquid; the hydrophilic functional molecules and the hydrophobic functional molecules form the host-guest characteristic film with certain mechanical strength and stability at the interface between the hydrophilic membrane and the hydrophobic membrane through hydrogen bonding; the liquid-based composite porous membrane unit is located in the gating body, and a gas input channel and a gas output channel are respectively provided on both sides of the liquid-based composite porous membrane unit, and the gas input channel and the gas output channel constitute the gas channel.

7. A host-guest-hydrogen-bond liquid gating system as claimed in claim 6, characterized in that: The door control body comprises two clamping members and a sealing material; the sealing material cooperates with the two clamping members at the connection point to achieve a sealed connection.

8. A method for in-situ formation of a host-guest thin film, comprising the following steps: Step 1, selecting a water-based functional liquid and a hydrophobic-based functional liquid, and a hydrophilic membrane and a hydrophobic membrane that can at least partially wet; Step 2: the hydrophilic membrane is immersed in a water-based functional liquid, the hydrophobic membrane is immersed in a hydrophobic functional liquid, and then the two membranes are stacked and placed in a gated body; Step three, the hydrophilic functional molecules in the water-based functional liquid and the hydrophobic functional molecules in the hydrophobic functional liquid form the host-guest characteristic film with certain mechanical strength and stability through hydrogen bonding at the interface between the hydrophilic film and the hydrophobic film; after the transmembrane pressure of the host-guest characteristic film is stabilized, the host-guest film is obtained.

9. The method for in-situ formation of a host-guest thin film according to claim 8, characterized in that: Step one, the hydrophilic membrane includes at least one of nylon membrane, mixed cellulose membrane, copper mesh, and polyvinyl alcohol membrane; the hydrophobic membrane includes at least one of polyvinylidene fluoride membrane and polytetrafluoroethylene membrane; the water-based functional solution includes at least one of water, α-cyclodextrin, β-cyclodextrin or γ-cyclodextrin aqueous solution; the hydrophobic functional liquid includes at least one of crude oil, alkanes, silicone oil, perfluoroalkanes, and aromatic hydrocarbons.

10. The method for in-situ formation of a host-guest thin film according to claim 8, characterized in that: In step 3, the stabilization time is at least 2 hours.

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