Large-steric-hindrance nano silicon dioxide as well as preparation and use methods thereof

Abstract

The invention discloses large-steric-hindrance nano silicon dioxide as well as a preparation method and application thereof. The large-steric-hindrance nano silicon dioxide comprises the following components in parts by weight: 8-15 parts of nano silicon dioxide, 1-3 parts of an inner-layer modifier and 8-17 parts of an outer-layer modifier. By grafting and modifying the surfaces of the small-diameter nano silicon dioxide particles, the density of hydrophilic groups of the nano silicon dioxide is reduced, meanwhile, the grafted long-chain groups contribute to adhesion of the nano silicon dioxide to the rock surface, a large amount of nano silicon dioxide occupies the rock surface, and adhesion of a thickening agent to the rock surface is reduced; large steric hindrance groups are arranged on the surface of the modified nano silicon dioxide, so that the dosage of the nano silicon dioxide can be effectively reduced, small-particle-size silicon dioxide is prevented from aggregating thickening agent molecules, the thickening agent can be kept in a stretched state, flowing of the thickening agent in tiny pore channels is facilitated, and the fracturing modification effect is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field fracturing transformation, and particularly relates to a sterically hindered nano-silica and its preparation and use methods. Background Art

[0002] With the continuous growth of energy demand and the gradual reduction of traditional oil and gas resources, unconventional oil and gas reservoirs have become an important replacement area for oil and gas resources in China. According to statistics, unconventional oil and gas resources in China account for more than 40% of the proven recoverable reserves, with huge development potential. Hydraulic fracturing technology is a key technical means for the efficient development of unconventional reservoirs. Fracturing fluid plays a role in transmitting pressure and carrying proppants, and is the core of hydraulic fracturing. Domestic and foreign scholars have carried out a large amount of research work on reservoir damage caused by fracturing fluid in hydraulic fracturing, but mainly focused on aspects such as water sensitivity, water blockage, and residue damage, and paid less attention to the permeability damage caused by the adsorption and retention of thickener molecules in the rock porous medium. Through investigation, it is found that the adsorption and retention of thickener in the rock porous medium in laboratory experiments and on-site actual construction is an important cause of reservoir damage. At present, the adsorption and retention mechanism and law of thickener in the rock porous medium are not clearly understood, so that the adsorption and retention damage of thickener in fracturing fluid cannot be effectively controlled, restricting the development effect of unconventional oil and gas resources such as shale oil and gas and tight oil and gas.

[0003] The thickener is a water-soluble polymer compound, with a large number of hydrophilic groups on the molecular chain, having a strong adsorption effect on the rock surface, which will cause a large amount of thickener to remain in the reservoir and cannot be discharged, reducing the flow capacity of the post-fracture channels and seriously affecting the fracturing transformation effect. During the flowback stage, the thickener molecules in the well are broken into smaller molecules under the action of the breaker, and flow back to the ground under the pressure difference with the fluid. Most of the thickener molecules after gel breaking can maintain a linear structure in the flowing state and are easy to pass through the microchannels. However, once the thickener molecules are adsorbed and attached to the rock wall of the pore, due to the interaction between the groups between molecules, the molecular chains will entangle to form large molecular clusters, blocking the pores.

[0004] The prior art, as disclosed in Chinese Patent CN 102352233 A, discloses a low-damage small-molecule guar gum fracturing fluid. By taking advantage of the characteristic of small molecular weight of small-molecule guar gum, after the fracturing operation is completed, the molecular chains of the thickening agent are broken by an oxidant to form smaller molecular chains. Thus, on the one hand, the addition amount of guar gum can be reduced, and on the other hand, the molecular chains of the thickening agent entering the formation can be discharged from the formation as much as possible to reduce the damage to the formation. However, based on the research in the industry on the pore throats and fluid characteristics of low-permeability tight reservoirs (see "Variation Characteristics of Microscopic Pore Throats and Movable Fluids in the Xujiahe Formation of the Fourth Member in Xinchang, Western Sichuan", disclosed in "Petroleum Geology & Experiment", 2014, Vol. 36, No. 1) and the research on the adsorption and retention law of polymers (see "Research on the Adsorption and Retention Law and Performance Variation of Polymers", disclosed in "Chemical Engineering of Oil & Gas", 2011, Vol. 40, No. 6), it is found that the damage of the fracturing fluid in the tight reservoir is mainly due to the adsorption of high-molecular aggregates in the rock pore throats, resulting in a decrease in the radius of the rock pore throats, which is the main source of the damage of the fracturing fluid in the low-permeability reservoir. Therefore, although this technology reduces the addition amount of the high-molecular thickening agent - guar gum and increases its return discharge amount, it cannot break the adsorption blockage of the thickening agent of the high-molecular compound in the fracturing fluid on the reservoir rock, nor can it effectively solve the technical problem of the high-molecular aggregates adsorbed at the rock pore throats, and thus cannot effectively improve the oil and gas penetration channel environment of the reservoir. Therefore, to promote the efficient development of unconventional oil and gas resources, it is urgent to solve the problem of the damage of the thickening agent to the reservoir. Summary of the Invention

[0005] The object of the present invention is to provide a large steric hindrance nano-silica and its preparation and application methods to overcome the above technical defects.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The present invention first discloses a large steric hindrance nano-silica, which comprises the following components by weight: 8 - 15 parts of nano-silica, 1 - 3 parts of an inner layer modifier, and 8 - 17 parts of an outer layer modifier.

[0008] Preferably, the particle size of the nano-silica is 3 - 10 nm.

[0009] As a preferred scheme, the inner layer modifier is dimethoxyphenylmethylsilane.

[0010] As another preferred scheme of the present invention, the outer layer modifier is one or a mixture of 2,5-dihydroxy-1,4-benzoquinone and saccharide polyhydroxy compounds.

[0011] As a further preferred scheme, the saccharide polyhydroxy compound is one or several of glucose, mannose, galactose, xylose, and cellobiose.

[0012] The present invention further discloses a preparation method of sterically hindered nano-silica, comprising the following steps:

[0013] S1. Put 8-15 parts by weight of nano-silica into a reaction vessel, add 40-65 parts by weight of n-hexane, and stir until the nano-silica is completely suspended in the n-hexane;

[0014] S2. Then add 1-3 parts by weight of an inner layer modifier, and stir and react at room temperature for 30-60 min;

[0015] S3. Add 8-17 parts by weight of an outer layer modifier, and after the dropping is completed, raise the temperature to 50-60 °C, and react for 60-70 min under stirring conditions;

[0016] S4. Finally, remove the solvent by low-pressure rotary evaporation, wash three times with absolute ethanol, filter and dry at 90 °C to obtain modified nano-silica, which is the target product.

[0017] As a further preferred solution, in step S1, the stirring speed is 120-300 r / min.

[0018] Preferably, the inner layer modifier is dimethoxyphenylmethylsilane.

[0019] As a further preferred solution, the dropping time of the inner layer modifier should be controlled within 5 min.

[0020] Preferably, the outer layer modifier is one or a mixture of any several of 2,5-dihydroxy-1,4-benzoquinone, glucose, mannose, galactose, xylose, and cellobiose in any proportion.

[0021] As a further preferred solution, the dropping time of the outer layer modifier should be controlled within 30 min.

[0022] The present invention further discloses a usage method of any of the above-mentioned sterically hindered nano-silica or the sterically hindered nano-silica prepared by the above preparation method: injecting the sterically hindered nano-silica into a formation together with a fracturing fluid implemented on site, wherein the dosage of the sterically hindered nano-silica is 0.05-0.1% of the mass of the fracturing fluid implemented on site.

[0023] Adopting the above technical solution, the present invention has the following beneficial effects:

[0024] 1. The large steric hindrance nano-silica prepared by the present invention for reducing the entanglement of polymer compounds has the functions of changing the contact angle, improving the flexibility of thickener molecules, breaking hydrogen bonds, and forming steric hindrance to occupy adsorption sites, etc. It can promote the flowback of fracturing fluid, significantly increase the remaining polymer concentration in the flowback fluid, effectively reduce the adsorption and retention damage of polymers in the reservoir, fully release the post-fracture productivity, and significantly improve the fracturing treatment effect.

[0025] 2. Changing the contact angle: The hydrophilicity of the modified nano-silica, i.e., the large steric hindrance nano-silica, is reduced. The contact angle test results show that the contact angle of the rock sample thin slices soaked in clear water containing the modified nano-silica increases by more than 30°.

[0026] 3. Improving molecular flexibility: The thickener molecules curl and entangle into groups due to the hydrogen bond interaction between their molecules, resulting in a large hydration radius after gel breaking and easily blocking the oil and gas flow channels after transformation. The modified nano-silica, i.e., the large steric hindrance nano-silica of the present invention, can shield the hydrogen bond interaction between molecules, enhance the flexibility of the thickener molecules after gel breaking, keep them in a linear structure, and effectively reduce the hydration radius of the thickener.

[0027] 4. Reducing the core damage rate: The large steric hindrance nano-silica prepared by the present invention can effectively reduce the adhesion of the thickener on the rock surface and avoid the entanglement and aggregation of its molecular chains, ensuring good fluidity of the channel, and reducing the core damage rate of the gel-breaking fluid by more than 20%.

[0028] 5. Promoting the flowback effect: The large steric hindrance nano-silica prepared by the preparation method provided by the present invention is applied on site, and the final flowback rate of the applied well is increased by 66.4%.

[0029] 6. Remaining polymer concentration: The comparison result with the control well shows that the average remaining polymer concentration in the flowback fluid of the conventional polymer fracturing fluid is 960 mg / L, and the average concentration of the flowback fluid of the polymer low-damage fracturing fluid containing the prepared product, i.e., the large steric hindrance nano-silica, is 1488 mg / L, an increase of 35.5%.

[0030] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and implement it according to the content of the specification, the following will describe in detail with reference to the preferred embodiments of the present invention and the accompanying drawings. Brief Description of the Drawings

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other design solutions and drawings can also be obtained based on these drawings.

[0032] Figure 1 Cumulative hydration radius distribution diagram of the products obtained in Examples 1-4;

[0033] Figure 2 Curve for comparing flowback rates;

[0034] Figure 3 Curve for comparing the concentration curves of the remaining thickening agent in the flowback fluid;

[0035] To make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Specific Embodiments

[0036] The content of the present invention can be further understood by combining the following detailed description of the preferred implementation methods of the present invention and the included embodiments. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention belongs. If the definitions of specific terms disclosed in the prior art are inconsistent with any definitions provided in the present invention, the definitions of the terms provided in the present invention shall prevail.

[0037] In a typical embodiment of the present application, a large steric hindrance nano-silica is provided, which, by weight, comprises the following components: 8-15 parts of nano-silica, 1-3 parts of an inner layer modifier, and 8-17 parts of an outer layer modifier.

[0038] Preferably, the particle size of the nano-silica is 3-10 nm.

[0039] In a preferred embodiment, the inner layer modifier is dimethoxyphenylmethylsilane.

[0040] In another preferred embodiment, the outer layer modifier is one or a mixture of 2,5-dihydroxy-1,4-benzoquinone and saccharide polyhydroxy compounds.

[0041] In a further preferred embodiment, the saccharide polyhydroxy compound is one or several of glucose, mannose, galactose, xylose, and cellobiose.

[0042] The present invention grafts and modifies the surface of nano-silica particles with a small diameter, reducing the density of hydrophilic groups on the nano-silica. At the same time, the grafted long-chain groups contribute to the attachment of nano-silica on the rock surface, occupying a large amount of the rock surface and reducing the attachment of the thickening agent on the rock surface; the large steric hindrance groups on the surface of the modified nano-silica can effectively reduce the dosage of nano-silica, avoid the aggregation of thickening agent molecules by small-sized silica, enable the thickening agent to maintain a stretched state, facilitate its flow in microchannels, and improve the fracturing effect.

[0043] In the second typical embodiment of the present invention, a preparation method of sterically hindered nano-silica is provided, including the following steps:

[0044] S1. Put 8-15 parts by weight of nano-silica into a reaction vessel, add 40-65 parts by weight of n-hexane, and stir until the nano-silica is completely suspended in the n-hexane;

[0045] S2. Then add 1-3 parts by weight of an inner layer modifier, and stir and react at room temperature for 30-60 min;

[0046] S3. Add 8-17 parts by weight of an outer layer modifier. After the dropping is completed, raise the temperature to 50-60 °C, and react for 60-70 min under stirring conditions;

[0047] S4. Finally, remove the solvent by low-pressure rotary evaporation, wash three times with absolute ethanol, filter and dry at 90 °C to obtain modified nano-silica, which is the target product.

[0048] In a further preferred embodiment, in step S1, the stirring speed is 120-300 r / min.

[0049] Preferably, in step S2, the inner layer modifier is dimethoxyphenylmethylsilane.

[0050] As a further preferred scheme, the dropping time of the inner layer modifier should be controlled within 5 min.

[0051] Preferably, in step S3, the outer layer modifier is one or a mixture of any several of 2,5-dihydroxy-1,4-benzoquinone, glucose, mannose, galactose, xylose, cellobiose in any proportion.

[0052] As a further preferred scheme, the dropping time of the outer layer modifier should be controlled within 30 min.

[0053] In the third typical embodiment of the present invention, the present invention further discloses any of the sterically hindered nano-silica or the sterically hindered nano-silica prepared by the above preparation method, and its usage method is: injecting the sterically hindered nano-silica into the formation together with the on-site fracturing fluid, wherein the dosage of the sterically hindered nano-silica is 0.05-0.1% of the mass of the on-site fracturing fluid.

[0054] The present invention will be further described below with reference to embodiments:

[0055] Example 1

[0056] This example relates to a preparation method of sterically hindered nano-silica, specifically:

[0057] Add 79 parts of n - hexane and 9 parts of nano - silica with a diameter of 7 nm into a three - necked flask, stir at a speed of 300 r / min to make the nano - silica completely suspended in n - hexane, dropwise add 2 parts of dimethoxyphenylmethylsilane, complete the addition in 10 min, stir at a rotation speed of 200 r / min at room temperature for 60 min, then dropwise add 10 parts of 2,5 - dihydroxy - 1,4 - benzoquinone, after completing the addition in 20 min, raise the reaction temperature to 60 °C, react with stirring for 70 min. After the reaction is completed, remove cyclohexane by rotary evaporation under low pressure, then wash three times with anhydrous ethanol (20 parts of anhydrous ethanol for each wash), filter and dry at 90 °C for 6 h to obtain modified nano - silica, which is the large - steric - hindrance nano - silica.

[0058] Example 2

[0059] This example relates to a preparation method of large - steric - hindrance nano - silica, specifically as follows:

[0060] Add 70 parts of n - hexane and 13 parts of nano - silica with a diameter of 10 nm into a three - necked flask, stir at a speed of 300 r / min to make the nano - silica completely suspended in n - hexane, dropwise add 3 parts of dimethoxyphenylmethylsilane, complete the addition in 10 min, stir at a rotation speed of 200 r / min at room temperature for 60 min, then dropwise add 14 parts of glucose, after completing the addition in 20 min, raise the reaction temperature to 60 °C, react with stirring for 70 min. After the reaction is completed, remove cyclohexane by rotary evaporation under low pressure, then wash three times with anhydrous ethanol (20 parts of anhydrous ethanol for each wash), filter and dry at 90 °C for 6 h to obtain modified nano - silica, which is the large - steric - hindrance nano - silica.

[0061] Example 3

[0062] This example relates to a preparation method of large - steric - hindrance nano - silica, specifically as follows:

[0063] Add 75 parts of n - hexane and 8 parts of nano - silica with a diameter of 3 nm into a three - necked flask, stir at a speed of 300 r / min to make the nano - silica completely suspended in n - hexane, dropwise add 2 parts of dimethoxyphenylmethylsilane, complete the addition in 10 min, stir at a rotation speed of 200 r / min at room temperature for 60 min, then dropwise add 15 parts of mannose, after completing the addition in 20 min, raise the reaction temperature to 60 °C, react with stirring for 70 min. After the reaction is completed, remove cyclohexane by rotary evaporation under low pressure, then wash three times with anhydrous ethanol (20 parts of anhydrous ethanol for each wash), filter and dry at 90 °C for 6 h to obtain modified nano - silica, which is the large - steric - hindrance nano - silica.

[0064] Example 4

[0065] This example relates to a method for preparing sterically hindered nano-silica, specifically as follows:

[0066] Add 68 parts of n-hexane and 13 parts of nano-silica with a diameter of 6 nm into a three-necked flask, stir at a speed of 300 r / min to make the nano-silica completely suspended in n-hexane, dropwise add 3 parts of dimethoxyphenylmethylsilane, complete the dropwise addition in 10 min, stir at a rotation speed of 200 r / min at room temperature for 60 min, then dropwise add 6 parts of mannose and 10 parts of galactose, after completing the dropwise addition in 20 min, raise the reaction temperature to 60 °C, react under stirring for 70 min, after the reaction is completed, remove cyclohexane by rotary evaporation under low pressure, then wash three times with anhydrous ethanol (20 parts of anhydrous ethanol for each wash), filter and dry at 90 °C for 6 h to obtain modified nano-silica, which is sterically hindered nano-silica.

[0067] Perform the following performance tests on the modified nano-silica obtained in Examples 1-4:

[0068] (1) Contact angle

[0069] The hydrophilicity of the modified nano-silica is reduced. Use contact angle measurement to compare the modification effect of silica.

[0070] Take 0.2 g each of unmodified silica and the modified nano-silica obtained in Examples 1-4 and disperse them into 100 mL of clear water. Immerse the tested rock thin slice in the prepared solution, and test the contact angle of the rock thin slice after soaking with clear water. The test results are shown in Table 1.

[0071] Table 1 Contact angles of products in different examples

[0072] Serial number Product Contact angle / ° 1 Unmodified 35.7 2 Example 1 75.3 3 Example 2 69.8 4 Example 3 72.6 5 Example 4 70.7

[0073] As can be seen from Table 1, the products prepared by modification can effectively increase the contact angle of the rock surface and reduce the hydrophilicity of nano-silica.

[0074] (2) Hydration radius

[0075] The modified nano-silica can effectively reduce the entanglement of thickener molecules, resulting in a reduction in the hydration radius of the thickener. By testing the hydration radius of the thickener containing nano-silica, the modification effect of nano-silica is confirmed.

[0076] Specific operation process: Take 0.2 g each of unmodified silica and the modified nano-silica obtained in Examples 1-4, add them into 100 mL of a gel-breaking fluid for oilfield fracturing fluid with a mass fraction of 1%, stir evenly, and test the hydration radius of the thickener containing nano-silica through a laser particle size analyzer. The test results are shown in Figure 1 and Table 2.

[0077] Table 2 Median distribution of hydration radius of breaker fluid containing products of different examples

[0078] Serial number Product Median hydration radius / μm 1 Unmodified 8.16 2 Example 1 2.86 3 Example 2 2.78 4 Example 3 2.69 5 Example 4 2.12

[0079] As can be seen from Table 2, after adding the modified product, the hydration radius of the breaker fluid decreased significantly, indicating that the entanglement effect of the thickener molecules was effectively reduced, making them more flexible.

[0080] (3) Core damage

[0081] The core damage test was carried out according to SY / T5107 "Performance Evaluation Standard for Water-based Fracturing Fluids". The test results of the core damage rate are shown in Table 3.

[0082] Table 3 Damage test of core permeability by breaker fluid containing products of different examples

[0083]

[0084] The modified nano-silica prepared in Examples 1-4 can effectively reduce the adhesion of the thickener on the rock surface, avoid the entanglement and aggregation of the thickener molecular chains, and reduce pore plugging; at the same time, a large number of hydroxyl groups are contained on the surface of nano-silica, which can be dispersed in the aqueous fluid and act on the thickener molecular chains. After adding the modified product, the damage of the breaker fluid to the core permeability decreased significantly, and as can be seen from Table 3, the reduction amplitude of the core damage rate reached more than 20%.

[0085] Application Example 1

[0086] The liquid preparation was carried out according to Q / SY CQ0154 "On-site Preparation and Quality Requirements for Fracturing and Acidizing Working Fluids"

[0087] The modified nano-silica of Example 3 was added to the on-site fracturing fluid system, and the adjacent well without adding modified silica in the on-site fracturing fluid system was used as the control example.

[0088] After the fracturing construction was completed, the backflow volume of the backflow fluid was counted irregularly. The ratio of the backflow volume to the fluid volume injected into the well was the backflow rate, and the obtained backflow rate comparison chart was drawn, as Figure 2 shown.

[0089] As Figure 2 can be seen, the comparison results between the application well and the control well showed that the final backflow rate of the application well increased by 66.4%.

[0090] Application Example 2

[0091] After the fracturing construction was completed, the backflow fluid was taken at regular intervals, and the concentration of the remaining thickener in the backflow fluid was measured using an ultraviolet spectrophotometer. The obtained comparison chart of the concentration of the remaining thickener in the backflow fluid was drawn, as Figure 3 shown.

[0092] It can be seen from Figure 3 that the comparison results between the application well and the comparison well show that the average concentration of the remaining thickener in the flowback fluid of the application well has increased by 35.35%.

[0093] The above are only the preferred embodiments of the present invention, which are merely illustrative of the present invention rather than limiting the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A large steric hindrance nano-silicon dioxide, characterized in that: The invention comprises the following components by weight: 8 to 15 parts of nano silicon dioxide, 1 to 3 parts of inner layer modifier and 8 to 17 parts of outer layer modifier.

2. The large steric hindrance nano-silicon dioxide as claimed in claim 1, characterized in that: The particle size of the nano silicon dioxide is 3-10 nm.

3. The large steric hindrance nano-silicon dioxide as claimed in claim 1, characterized in that: The inner layer modifier is dimethoxyphenylmethylsilane.

4. The large steric hindrance nano-silicon dioxide as claimed in claim 1, characterized in that: The outer layer modifier is one of 2,5-dihydroxy-1,4-benzquinone, sugar polyhydroxy compounds or a mixture thereof.

5. The large steric hindrance nano-silicon dioxide as claimed in claim 1, characterized in that: The sugar polyhydroxy compound is one or more of glucose, mannose, galactose, xylose and cellobiose.

6. A method for preparing large steric hindrance nano-silicon dioxide, characterized in that: The following steps are involved: S1, putting 8 to 15 parts by weight of nano-silicon dioxide into a reaction container, adding 40 to 65 parts by weight of n-hexane, and stirring until the nano-silicon dioxide is completely suspended in the n-hexane; S2, then add 1 to 3 parts by weight of an inner layer modifier, and stir and react at room temperature for 30 to 60 minutes; S3, adding 8 to 17 parts by weight of an outer layer modifier, raising the temperature to 50 to 60° C. after the addition is complete, and reacting for 60 to 70 minutes under stirring; S4, finally removing the solvent by low-pressure rotary evaporation, washing three times with anhydrous ethanol, filtering and drying at 90° C. to obtain modified nano-silica, which is the target product.

7. The method for preparing large steric hindrance nano-silicon dioxide according to claim 6, characterized in that: In the step S2, the inner layer modifier is dimethoxyphenylmethylsilane, and the dropwise addition time of the inner layer modifier should be controlled within 5 minutes.

8. The method for preparing large steric hindrance nano-silicon dioxide according to claim 6, characterized in that: In the step S3, the outer layer modifier is one of 2,5-dihydroxy-1,4-benzquinone, glucose, mannose, galactose, xylose, and cellobiose, or a mixture of any of them in any proportion.

9. The method for preparing large steric hindrance nano-silicon dioxide according to claim 6, characterized in that: In the step S3, the dropwise addition time of the outer layer modifier should be controlled within 30 minutes.

10. An application of large steric hindrance nano-silicon dioxide, comprising the large steric hindrance nano-silicon dioxide according to any one of claims 1 to 5 or the large steric hindrance nano-silicon dioxide prepared by the preparation method according to any one of claims 6 to 9, characterized in that: The method of use is: injecting the large steric hindrance nano silicon dioxide into the formation together with the on-site fracturing fluid, wherein the amount of the large steric hindrance nano silicon dioxide is 0.05-0.1% of the mass of the on-site fracturing fluid.

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