C8 modified SiO2 nanomaterial, and preparation method and application thereof

Abstract

The application provides a C8 modified SiO2 nanomaterial, a preparation method and application thereof. Based on surface modification technology of SiO2 nanoballs, the C8 modified SiO2 nanomaterial is successfully prepared, the particle size of which is 50 nm, and the C8 modified SiO2 nanomaterial has good interface effect. The compatibility, stability and surface tension of the C8 modified SiO2 nanomaterial are tested, and the C8 modified SiO2 nanomaterial has good compatibility, stability and oil displacement capacity.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, and in particular to a C8-modified SiO2 nanomaterial, its preparation method, and its application. Background Technology

[0002] Oil extraction can be divided into three stages. Primary oil recovery relies on formation energy for self-flowing extraction, producing approximately 5%-20% of the reserves. After the formation energy is released, artificial water or gas injection is used to replenish the reservoir energy and maintain formation pressure, allowing for continuous crude oil extraction. This is called secondary oil recovery, with a recovery rate of approximately 15%-20%. After several decades of secondary oil recovery, the remaining oil is trapped in discontinuous oil clumps within the sandstone pores of the reservoir. At this point, the produced fluid contains 85%-90% water, sometimes even as high as 98%, making extraction no longer economically viable. Therefore, approximately 60%-70% of the crude oil must be extracted using other physical and chemical methods; this type of extraction is called tertiary oil recovery, also known internationally as EOR (Enhanced Oil Recovery) technology.

[0003] Currently, polymer-clean fracturing fluid flooding technology is widely used in my country's tertiary oil recovery technology. However, using polymer flooding results in a large amount of polymer remaining underground, causing waste and difficulties in producing fluid treatment. Furthermore, in many blocks, oil production declines rapidly after polymer injection.

[0004] Therefore, improving the existing polymer-based clean fracturing fluid system to increase oil recovery rate is an urgent problem to be solved in oilfield development. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention proposes a C8-modified SiO2 nanomaterial, its preparation method, and its applications.

[0006] In a first aspect, the present invention proposes a C8-modified SiO2 nanomaterial, which comprises SiO2 nanospheres and octyltrimethoxysiloxy (-O-Si(OMe)2(CH2)7-CH3) grafted onto its surface, wherein the particle size of the C8-modified SiO2 nanomaterial is 10-80 nm.

[0007] As a specific embodiment of the present invention, the C8 modified SiO2 nanomaterial is prepared by a method including the following steps: subjecting SiO2 nanospheres to a reflux reaction with octyltrimethoxysilane.

[0008] Secondly, the present invention provides a method for preparing C8 modified SiO2 nanomaterials, comprising the following steps: subjecting SiO2 nanospheres to a reflux reaction with octyltrimethoxysilane.

[0009] As a specific embodiment of the present invention, the SiO2 nanospheres are prepared by sol-gel method using tetraethyl orthosilicate as the silicon source.

[0010] Specifically, the reaction equation is as follows:

[0011] nSi(OC2H5)4 + 4nH2O → nSi(OH)4 + 4nC2H5OH (hydrolysis)

[0012] nSi(OH)4→nSiO2+2nH2O (condensation)

[0013] As a specific embodiment of the present invention, the method for preparing SiO2 nanospheres includes the following steps:

[0014] S11: Mix tetraethyl orthosilicate with ethanol to obtain the first solution;

[0015] S12: Mix deionized water, concentrated ammonia, and ethanol to obtain a second solution;

[0016] S13: Mix the first solution and the second solution, stir and evaporate to obtain a concentrated solution;

[0017] S14: Add the concentrated solution obtained in step S13 to toluene liquid, stir, centrifuge and evaporate to obtain white SiO2 solid.

[0018] It should be noted that there are no limitations on the ethanol used in this invention. In order to calculate the ratio between ethanol and each reagent, anhydrous ethanol is used.

[0019] As a specific embodiment of the present invention, the volume ratio of tetraethyl orthosilicate to ethanol is (4-5):100.

[0020] In a specific embodiment of the present invention, in step S12, the volume ratio of deionized water, concentrated ammonia, and ethanol is (0.1-1):(5-10):80; and the concentration of the concentrated ammonia is 25%-28% by weight.

[0021] As a specific embodiment of the present invention, the mixing method of the first solution and the second solution is not limited, as long as they are mixed evenly. As a preferred embodiment of the present invention, the stirring method is preferably magnetic stirring, and the stirring time is preferably 0.5 to 2 hours.

[0022] As a specific embodiment of the present invention, in step S13, the mixing method of the first solution and the second solution is not limited. In order to make the reaction more complete, the first solution is preferably added to the second solution drop by drop by a burette. Preferably, the mixture is further mixed evenly by stirring. More preferably, the stirring time is 15 to 24 hours.

[0023] As a specific embodiment of the present invention, the evaporation method is preferably rotary evaporation, and the specific parameters are preferably: pressure below 0.01 MPa and temperature between 20 and 50°C.

[0024] As a specific embodiment of the present invention, the concentrate is concentrated to 5% to 10% of its original volume.

[0025] In a specific embodiment of the present invention, the method of adding toluene to the concentrate in step S14 is not limited. In order to make the reaction more complete, it is preferable to add it drop by drop with a burette. For example, for 6 ml of concentrate, the addition rate can be 1 d / s.

[0026] As a specific embodiment of the present invention, the stirring method is preferably high-speed stirring with a rotor for 1 to 5 minutes.

[0027] As a specific embodiment of the present invention, the centrifugation is performed by washing with anhydrous ethanol at least three times.

[0028] As a specific embodiment of the present invention, the method for preparing C8 modified SiO2 nanomaterials includes the following steps:

[0029] S21: Add SiO2 obtained in step S14 to toluene containing octyltrimethoxysilane, and reflux in an oil bath for 4 hours to obtain a mixture;

[0030] S22: Centrifuge the mixture obtained in step S21, wash it with toluene and dry it to obtain C8 modified SiO2 nanomaterials.

[0031] Specifically, the reaction equation for preparing C8 modified SiO2 nanomaterials using octyltrimethoxysilane and the prepared nano-SiO2 as raw materials and employing an oil bath reflux method is as follows:

[0032]

[0033] As a specific embodiment of the present invention, in step S21, the ratio of the amount of SiO2 nanospheres to octyltrimethoxysilane is 1g:0.2-0.9mmol; preferably, 1g:0.4-0.8mmol; for example, 1g:0.6mmol.

[0034] Preferably, the volume ratio of octyltrimethoxysilane to toluene is (0.1-0.5):6.

[0035] Preferably, the volume-to-mass ratio of the toluene containing octyltrimethoxysilane to SiO2 is 5-10 ml: 1 g; more preferably, it is 6-7 ml: 1 g.

[0036] In a specific embodiment of the present invention, the oil bath temperature is 100-120°C.

[0037] In a specific embodiment of the present invention, the oil bath reflux time is 3 to 6 hours.

[0038] All of the above-mentioned raw materials used in this invention can be prepared in-house or purchased commercially; this invention does not impose any particular limitations on them.

[0039] Thirdly, the present invention provides the application of the C8 modified SiO2 nanomaterial in the field of fracturing fluid.

[0040] As a specific embodiment of the present invention, C8 modified SiO2 nanomaterials are uniformly dispersed in existing fracturing fluid.

[0041] In a specific embodiment of the present invention, the amount of C8 modified SiO2 nanomaterial added is 0.1% to 2%;

[0042] As a specific embodiment of the present invention, the dispersion method is preferably a combination of ultrasonic and mechanical stirring; the dispersion time of SiO2-C8 nanomaterials is 3 to 10 hours; preferably, the dispersion time is 5 hours.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0044] 1. Based on the surface modification technology of SiO2 nanospheres, this invention successfully prepared C8 modified SiO2 nanomaterials and tested their compatibility, stability and surface tension. They have good compatibility, stability and oil displacement ability.

[0045] 2. The C8-modified SiO2 nanomaterials synthesized in this invention have a particle size of 50 nm and exhibit good interfacial effects. Simultaneously, a method for synthesizing and modifying nanoparticles applicable to fracturing fluid systems has been established, enabling the nanoparticles to be well dispersed in polymer-cleaned fracturing fluids and exhibiting excellent compatibility and stability. Attached Figure Description

[0046] Figure 1 This is a schematic diagram illustrating the formation process of monodisperse nano-SiO2 spherical particles according to an embodiment of the present invention;

[0047] Figure 2 Infrared spectra of SiO2 nanomaterials and C8-modified SiO2 nanomaterials;

[0048] Figure 3a SEM image (50x) of C8 modified SiO2 nanomaterial microspheres;

[0049] Figure 3b SEM image (100x) of C8 modified SiO2 nanomaterial microspheres;

[0050] Figure 4a Elemental analysis diagram of C in C8 modified SiO2 nanomaterials;

[0051] Figure 4b H elemental analysis diagram of C8 modified SiO2 nanomaterials;

[0052] Figure 4c Elemental analysis of nitrogen in C8-modified SiO2 nanomaterials;

[0053] Figure 5 Compatibility and stability of C8-modified SiO2 nanomaterials in fracturing fluids;

[0054] Figure 6 This is a bar chart showing the dispersion time of C8-modified SiO2 nanomaterials with different concentration ratios in fracturing fluid in Example 2.

[0055] Figure 7a The rheological properties of medium-viscosity fracturing fluid-SiO2 nanomaterial colloid solution without C8 modification are shown in the graph.

[0056] Figure 7b The rheological properties of medium-viscosity fracturing fluid-C8 modified SiO2 nanomaterial adhesive are shown in the graph.

[0057] Figure 7c The rheological properties test results of high-viscosity fracturing fluid-unmodified SiO2 nanomaterial colloid are shown in the figure.

[0058] Figure 7d The rheological properties of the high-viscosity fracturing fluid-C8 modified SiO2 nanomaterial adhesive are shown in the graph.

[0059] Among them, the infrared spectrum curves of 1-SiO2 nanomaterials and 2-C8 modified SiO2 nanomaterials are shown. Detailed Implementation

[0060] The present invention will be further described below with reference to specific embodiments, but this does not constitute any limitation on the present invention.

[0061] The water-based fracturing fluid mainly comprises: 0.2-0.45% thickener, 0.3% crosslinking agent, 2% KCl, 0.1% flow aid, 1% nano-displacement agent, and the remainder is water. The medium-viscosity fracturing fluid used in the embodiments of this invention has a viscosity of 16 mPa·s and contains 0.2% thickener; the high-viscosity fracturing fluid has a viscosity of 34 mPa·s and contains 0.35% thickener.

[0062] In the elemental analysis experiments of the various embodiments of the present invention, the experimental instrument was a Thermo Fisher Scientific Flash EA1112 CHNS-0 elemental analyzer; the experimental parameters were: furnace temperature 900℃, detector temperature 65℃, reference gas (He): 100ml / min; carrier gas (He): 140ml / min; oxygen: 140ml / min.

[0063] In each embodiment of the present invention, the surface tension coefficient is tested using the capillary method.

[0064] In the various embodiments of the present invention, the interfacial tension test was conducted using a German KRUSS interfacial tension meter, model K100.

[0065] Example 1

[0066] This embodiment provides a C8-modified SiO2 nanomaterial, its preparation method, and its application. SiO2 nanospheres and C8-modified SiO2 nanomaterials are prepared. Specific details are as follows:

[0067] Step 1: Synthesis of SiO2 nanospheres

[0068] S11: Mix 4.6 ml of TEOS with 100 ml of anhydrous ethanol and stir with a magnetic stirrer at room temperature for 1 h to obtain the first solution;

[0069] S12: Mix 0.4 ml of deionized water, 7.6 ml of 25% by weight concentrated ammonia solution and 80 ml of anhydrous ethanol and stir with a magnetic stirrer at room temperature for 1 h to obtain the second solution;

[0070] S13: Add the first solution dropwise to the second solution using an acid burette, and stir at room temperature for 20 hours to obtain a mixed solution;

[0071] S14: The mixed liquid is subjected to rotary evaporation at a negative pressure of -0.095MPa and a temperature of 35℃, and concentrated to 6 ml to obtain a concentrated solution;

[0072] S15: Add the concentrated solution dropwise to 10 ml of toluene using an acid burette at a rate of 1 d / s, stir at high speed with a rotor for 2 min, wash with anhydrous ethanol, centrifuge three times, and allow it to evaporate naturally to obtain white SiO2 solid.

[0073] Step 2: Synthesis of C8-modified SiO2 nanomaterials

[0074] S21: Mix 0.6 mmol of octyltrimethoxysilane with 6 ml of toluene, add 1 g of SiO2, and reflux in an oil bath at 105 °C for 4 h to obtain a mixture;

[0075] S22: The mixture is centrifuged, washed with toluene, and dried to obtain C8 modified SiO2 nanomaterials.

[0076] The C8-modified SiO2 nanomaterials obtained in Example 1 were subjected to infrared spectroscopy analysis, such as... Figure 2 As shown, the infrared spectral characteristic peaks of the C8-modified SiO2 nanomaterials obtained in Example 1 are compared with those of existing SiO2 nanomaterials, indicating that the C8 grafting on the surface of the SiO2 nanomaterials prepared in Example 1 was successful.

[0077] The C8-modified SiO2 nanomaterials obtained in Example 1 were observed by SEM scanning electron microscopy, as shown in Figures 3a and 3b. The average particle size of the C8-modified SiO2 nanomaterials obtained in Example 1 was 50 nm.

[0078] Elemental analysis was performed on the C8-modified SiO2 nanomaterials and SiO2 nanospheres obtained in Example 1, such as... Figure 4a , 4b As shown in Figure 4c and Data List 1, it also indicates that C8 grafting on the SiO2 surface was successful.

[0079] Table 1. Elemental analysis of C, H, and N in C8-modified SiO2 nanomaterials

[0080] sample C(％) H(％) N(％) <![CDATA[SiO2]]> 0.000 3.797 0.000 <![CDATA[SiO2-C8]]> 4.540 2.328 0.000

[0081] The C8-modified SiO2 nanomaterials obtained in Example 1 were dispersed in medium-viscosity fracturing fluid at a ratio of 0.5%, allowed to stand overnight, and the agglomeration of nanoparticles was observed. Figure 5 As shown, the results indicate that C8-modified SiO2 nanomaterials exhibit good compatibility and stability in fracturing fluids.

[0082] Example 2

[0083] This embodiment provides the application of the C8 modified SiO2 nanomaterials prepared in Example 1 in fracturing fluid, and obtains an optimal formulation, the details of which are as follows:

[0084] 0.02 g, 0.1 g, 0.2 g, and 0.4 g of the C8-modified SiO2 nanomaterials prepared in Example 1 were taken and dispersed in 20 ml of pre-prepared fracturing fluid to obtain fracturing fluids with proportions of 0.1%, 0.5%, 1%, and 2%, respectively. The dispersibility of the fracturing fluids was tested by ultrasonic treatment combined with mechanical stirring.

[0085] Distributed test results, such as Figure 6As shown, C8-modified SiO2 nanomaterials exhibit the best dispersibility at a concentration of 0.5%, with a dispersion time of only 4 hours. The optimal concentration of C8-modified SiO2 nanomaterials is 0.5%, followed by 1%.

[0086] Test case

[0087] This test example involves various performance tests on the fracturing fluids with different formulations obtained in Example 2, and comparisons are made with SiO2 nano-fracturing fluids. Specific details are as follows:

[0088] The SiO2 nanospheres prepared in step 1 of Example 1 were also dispersed in medium-viscosity fracturing fluid at proportions of 0.1%, 0.5%, 1%, and 2% respectively, using an ultrasonic-mechanical stirring method for 4 hours to obtain 0.1% SiO2 nano-medium-viscosity fracturing fluid, 0.5% SiO2 nano-medium-viscosity fracturing fluid, 1% SiO2 nano-medium-viscosity fracturing fluid, and 2% SiO2 nano-medium-viscosity fracturing fluid. These were compared with the 0.1% SiO2-C8 nano-medium-viscosity fracturing fluid, 0.5% C8-modified SiO2 nanomaterial medium-viscosity fracturing fluid, 1% SiO2-C8 nano-medium-viscosity fracturing fluid, and 2% C8-modified SiO2 nanomaterial medium-viscosity fracturing fluid obtained in Example 2. Various comparative tests were then performed.

[0089] Surface tension coefficient test

[0090] The surface tension coefficients of the medium-viscosity fracturing fluids and C8-modified SiO2 nanomaterials prepared at proportions of 0.1%, 0.5%, 1%, and 2% were tested using the capillary method. The results are shown in Table 2.

[0091] Table 2 shows the results of surface tension coefficient measurements for fracturing fluids with different formulations obtained in Example 2.

[0092]

[0093] The results show that the addition of C8 modified SiO2 nanomaterials can effectively reduce the surface tension coefficient of fracturing fluid, which is beneficial to avoiding damage to the reservoir caused by water-locking effect and Jamin effect.

[0094] Rheological performance testing

[0095] The above-mentioned formulations were then dispersed in high-viscosity fracturing fluids: 0.1% C8-modified SiO2 nanomaterial high-viscosity fracturing fluid, 0.5% C8-modified SiO2 nanomaterial high-viscosity fracturing fluid, 1% C8-modified SiO2 nanomaterial high-viscosity fracturing fluid, and 2% C8-modified SiO2 nanomaterial high-viscosity fracturing fluid. A comparative test was conducted with the high-viscosity fracturing fluids prepared in Example 2 with different proportions of C8-modified SiO2 nanomaterials, as shown in Figure 7. Figure 7a and Figure 7b The rheological curves of medium-viscosity fracturing fluid before and after the addition of 1% C8 modified SiO2 nanomaterials were compared. Figure 7c and 7d Rheological curves of high-viscosity fracturing fluid before and after the addition of 1% C8 modified SiO2 nanomaterials.

[0096] fracturing fluid interfacial tension test

[0097] C8-modified SiO2 nanomaterials at a ratio of 1% were added to medium-viscosity and high-viscosity fracturing fluids, respectively. The interfacial tension of the fracturing fluids before and after the addition of 1% C8-modified SiO2 nanomaterials was tested, and the results are shown in Tables 3 and 4.

[0098] Table 3. Surface tension of fracturing fluid before and after addition of 1% C8 modified SiO2 nanomaterials.

[0099]

[0100] Table 4. Interfacial tension of fracturing fluid before and after addition of 1% C8 modified SiO2 nanomaterials

[0101]

[0102] Experimental results show that the surface tension of the fracturing fluid was significantly reduced after adding C8 modified SiO2 nanomaterials. The fracturing fluid with added nanomaterials showed a significant reduction in surface tension, indicating a good oil displacement effect.

[0103] In summary, the C8-modified SiO2 nanomaterials of this invention have a particle size of 50 nm and exhibit good interfacial effects. Furthermore, a method for synthesizing and modifying nanoparticles applicable to fracturing fluid systems has been developed, enabling the nanoparticles to be well dispersed in polymer-cleaned fracturing fluids and exhibiting excellent compatibility and stability.

[0104] Any numerical value mentioned in this invention, if there is only a two-unit interval between any minimum and any maximum value, includes all values ​​that increase by one unit each time from the minimum to the maximum value. For example, if the amount of a component, or the value of a process variable such as temperature, pressure, or time, is stated as 50-90, in this specification it means specifically listing values ​​such as 51-89, 52-88… and 69-71 and 70-71, etc. For non-integer values, it may be appropriately considered that a unit is 0.1, 0.01, 0.001, or 0.0001. These are merely some specifically specified examples. In this application, in a similar manner, all possible combinations of numerical values ​​between the listed minimum and maximum values ​​are considered to have been disclosed.

[0105] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on 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 terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. An application of C8-modified SiO2 nanomaterial in fracturing fluids, characterized in that, The SiO2 nanomaterial comprises SiO2 nanospheres and octyltrimethoxysiloxy groups (-O-Si(OMe)2(CH2)7-CH3) grafted onto their surface, and the particle size of the SiO2 nanomaterial is 10-80 nm. C8-modified SiO2 nanomaterials were uniformly dispersed in fracturing fluid, with the addition amount of C8-modified SiO2 nanomaterials ranging from 0.5% to 1%. The C8-modified SiO2 nanomaterials are prepared by a method comprising the following steps: subjecting SiO2 nanospheres to a reflux reaction with octyltrimethoxysilane. The steps for reflux reaction of SiO2 nanospheres with octyltrimethoxysilane include: S21: Octyltrimethoxysilane is mixed with toluene, then SiO2 nanospheres are added, and the mixture is heated under reflux to obtain a mixture; S22: Centrifuge the mixture obtained in step S21, wash it with toluene and dry it to obtain C8 modified SiO2 nanomaterials.

2. The application according to claim 1, characterized in that, The SiO2 nanospheres were prepared using tetraethyl orthosilicate as the silicon source via a sol-gel method.

3. The application according to claim 2, characterized in that, The method for preparing SiO2 nanospheres includes the following steps: S11: Mix tetraethyl orthosilicate with ethanol to obtain the first solution; S12: Mix deionized water, concentrated ammonia, and ethanol to obtain a second solution; S13: Mix the first solution and the second solution, stir and evaporate to obtain a concentrated solution; S14: Add the concentrated solution obtained in step S13 to toluene, stir, centrifuge and evaporate to obtain white SiO2 solid.

4. The application according to claim 3, characterized in that, In step S11, the volume ratio of tetraethyl orthosilicate to ethanol is (4~5):

100.

5. The application according to claim 3 or 4, characterized in that, In step S12, the volume ratio of deionized water, concentrated ammonia, and ethanol is (0.1~1):(5~10):80; and / or The concentration of the concentrated ammonia solution is 25% to 28% by weight.

6. The application according to claim 3 or 4, characterized in that, In step S13, the first solution is added to the second solution dropwise using a burette; and / or The evaporation method is rotary evaporation, with the following specific parameters: pressure below 0.01 MPa, temperature between 20 and 50°C; and / or The concentrate is concentrated to 5% to 10% of its original volume.

7. The application according to claim 3 or 4, characterized in that, In step S14, the toluene concentrate is added dropwise using a burette; and / or The sample was washed with anhydrous ethanol at least three times before centrifugation.

8. The application according to claim 1, characterized in that, In step S21, the ratio of SiO2 nanospheres to octyltrimethoxysilane is 1g:0.2~0.9mmol; And / or, in step S21, the volume ratio of octyltrimethoxysilane to toluene is (0.1~0.5):6; And / or, in step S21, the volume-to-mass ratio of toluene containing octyltrimethoxysilane to SiO2 nanospheres is 5-10 ml: 1 g; and / or The heating temperature is 100~120℃; and / or The heating reflux time is 3~6 hours.

9. The application according to claim 8, characterized in that, In step S21, the ratio of SiO2 nanospheres to octyltrimethoxysilane is 1g:0.4~0.8mmol; And / or, in step S21, the volume-to-mass ratio of toluene containing octyltrimethoxysilane to SiO2 nanospheres is 6-7 ml: 1 g.

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