A slickwater and a method of making the same

Abstract

The application discloses slick water and a preparation method thereof, and belongs to the technical field of downhole working fluid. Raw materials for preparing the slick water include modified nano silicon dioxide 1-3 parts by weight, a drag reduction agent 0.05-0.2 parts by weight, a fluorine-containing surfactant 0.01-0.02 parts by weight, a cleanup agent 0.01-0.05 parts by weight, a clay stabilizer 0.1-0.5 parts by weight and water 100-110 parts by weight. The provided slick water has good reservoir protection and reservoir wetting reverse characteristics by using modified nano silicon dioxide, long-branched polyacrylamide, the fluorine-containing surfactant and other additives. The application is suitable for slick water fracturing systems of hydraulic fracturing.

Description

Technical Field

[0001] This invention belongs to the field of downhole working fluid technology in oil and gas field development, and relates to a slickwater, specifically a slickwater and its preparation method. Background Technology

[0002] Slickwater is a fracturing fluid system used in hydraulic fracturing of shale oil and gas reservoirs, and is one of the key fluids in oil and gas development. Compared with traditional gel fracturing fluid systems, slickwater fracturing fluid systems are widely used in oil and gas development due to their high efficiency and low cost. With the increasing technical requirements for tight reservoir development, the upgrading of fracturing fluids is crucial, especially in the development of ultra-low permeability reservoirs. In addition to basic proppant carrying and fracture network stimulation capabilities, fracturing fluids must also possess additional properties such as not damaging the reservoir, resistance to high salinity, and reservoir wetting reversal. Current slickwater fracturing technologies can cause varying degrees of reservoir damage. Summary of the Invention

[0003] The purpose of this invention is to provide a slickwater and its preparation method to improve reservoir protection during fracturing.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A slippery liquid, the raw materials for which it is made, by weight, include: 1-3 parts modified nano silica, 0.05-0.2 parts drag reducer, 0.01-0.02 parts fluorinated surfactant, 0.01-0.05 parts drainage aid, 0.1-0.5 parts clay stabilizer and 100-110 parts water.

[0006] As a limitation, the modified nano-silica is prepared by the following method: 20-25 parts by weight of nano-silica and 5-10 parts by weight of modifier are mixed in an ethanol solution, 1-3 parts by weight of catalyst are added to react, and the modified nano-silica is obtained after drying.

[0007] The modifier includes perfluorooctyltriethoxysilane, trimethoxyhexadecylsilane, or triethoxytridecylfluorooctylsilane; the catalyst includes p-toluenesulfonic acid, thionyl chloride, or trifluoromethanesulfonic acid.

[0008] As a further limitation, the reaction is carried out at a temperature of 60–80°C for a time of 4–6 hours.

[0009] As another limitation, the fluorinated surfactant includes (C7F) 15 CO2)2NHCH2COONa、(C7F 15 CO2)2NHCH2COONa or C7F 15 CONHCH2CH2COONa.

[0010] As a third limitation, the drainage aid includes nonylphenol polyoxyethylene ether or dodecyl alcohol polyoxyethylene ether.

[0011] As a fourth limitation, the clay stabilizer includes polydihydroxyethyl(2-hydroxy)propylammonium chloride.

[0012] As a fifth limitation, the drag-reducing agent is prepared by the following method: 75-80 parts by weight of acrylamide, 25-35 parts by weight of acrylic acid, 5-15 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid and 10-20 parts by weight of polymer monomer are mixed, the pH value is adjusted to 7-9, 1-2 parts by weight of ammonium persulfate, 0.5-1 parts by weight of sodium bisulfite, 1-2 parts by weight of diisobutylamidine hydrochloride and 1-2 parts by weight of initiator are added, and a polymerization reaction is carried out to obtain the drag-reducing agent;

[0013] The polymer monomer includes In the formula, n is 8, 10, 12 or 14; m is 8, 10, 12 or 20;

[0014] The initiator includes azovinylpyrazole or azobisisobutyramidine hydrochloride.

[0015] As a further limitation, the polymerization reaction is carried out at a temperature of 50–70°C for 3–4 hours.

[0016] As a further limitation, the polymer monomer is prepared by the following method: 3-5 parts by weight of polyoxyethylene ether compound, 3-6 parts by weight of acryloyl chloride and 50-70 parts by weight of acetone are mixed and reacted at 60-80°C for 8-10 hours to obtain the polymer monomer.

[0017] The polyoxyethylene ether compounds include octadecyl alcohol polyoxyethylene ether or isotridecyl alcohol polyoxyethylene ether.

[0018] The present invention also provides a method for preparing the above-mentioned slippery water, which involves mixing drag-reducing agent, fluorinated surfactant, drainage aid, clay stabilizer and water, and then adding modified nano-silica and mixing to obtain slippery water.

[0019] By adopting the above technical solution, the technical progress achieved by this invention compared with the prior art is as follows:

[0020] ①The present invention provides a slippery fluid, modified nano-silica can change the roughness and wettability of rock surface, fluorinated surfactant can further enhance the hydrophobicity of rock surface, long-branched polyacrylamide has good thickening and drag reduction properties, and together with other additives, the fracturing fluid system has good reservoir protection and reservoir wetting reversal characteristics.

[0021] ②The present invention provides a method for preparing slippery water, which has a simple preparation process and is suitable for industrial production. Detailed Implementation

[0022] The present invention will be further described in detail below through specific embodiments. It should be understood that the described embodiments are only for explaining the present invention and do not limit the present invention.

[0023] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art.

[0024] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0025] Example 1

[0026] This embodiment prepares a slippery liquid, specifically including the following steps:

[0027] S1. Preparation of modified nano-silica

[0028] 20 kg of nano-silica and 5 kg of perfluorooctyltriethoxysilane (modifier) ​​were mixed evenly in 30 kg of ethanol solution (anhydrous ethanol and water were mixed in a weight ratio of 5:1). 1 kg of p-toluenesulfonic acid (catalyst) was added, and the mixture was stirred continuously for 30 min to mix evenly. Then the temperature was raised to 60 °C and the reaction was carried out for 4 h. After drying to remove the reactants, modified nano-silica Al was obtained.

[0029] S2. Preparation of drag-reducing agents

[0030] Weigh out 3 kg of octadecyl alcohol polyoxyethylene ether and 3 kg of acryloyl chloride, mix them thoroughly, and then add 50 kg of acetone and mix. all uniform The reaction was carried out at 60℃ for 8 hours to obtain polymer monomer B1, whose structural formula is:

[0031] Take 75 kg of acrylamide, 25 kg of acrylic acid, 5 kg of 2-acrylamido-2-methylpropanesulfonic acid and 10 kg of polymer monomer B1 and mix them evenly. Add NaOH solution to adjust the pH value to 7.0. Add 1 kg of ammonium persulfate, 0.5 kg of sodium bisulfite, 1 kg of diisobutylamidine hydrochloride and 1 kg of azovinylpyrazole (initiator). Polymerize at 50°C for 3 h to obtain drag-reducing agent C1.

[0032] S3. Preparation of slippery water

[0033] 1 kg of modified nano-silica A1, 0.05 kg of drag reducer C1, and 0.01 kg of (C7F) were added. 15CO2)2NHCH2COONa, 0.01 kg of nonylphenol polyoxyethylene ether, 0.1 kg of poly(2-hydroxy)propylammonium chloride, and 100 kg of water are mixed to obtain slippery water D1.

[0034] Example 2

[0035] This embodiment prepares a slippery liquid, specifically including the following steps:

[0036] S1. Preparation of modified nano-silica

[0037] 25 kg of nano-silica and 10 kg of triethoxytridecylfluorooctylsilane (modifier) ​​were mixed evenly in 50 kg of ethanol solution (anhydrous ethanol and water were mixed in a weight ratio of 5:1). 3 kg of trifluoromethanesulfonic acid (catalyst) was added, and the mixture was stirred continuously for 30 min to mix evenly. Then the temperature was raised to 80 °C and the reaction was carried out for 6 h. After drying to remove the reactants, modified nano-silica A2 was obtained.

[0038] S2. Preparation of drag-reducing agents

[0039] Weigh 5 kg of isomeric tridecyl alcohol polyoxyethylene ether and 6 kg of acryloyl chloride, mix thoroughly, add 70 kg of acetone and mix thoroughly, react at 80°C for 10 h to obtain polymer monomer B2, whose structural formula is:

[0040] Take 80 kg of acrylamide, 35 kg of acrylic acid, 15 kg of 2-acrylamido-2-methylpropanesulfonic acid and 20 kg of polymer monomer B2 and mix them evenly. Add NaOH solution to adjust the pH value to 9.0. Add 2 kg of ammonium persulfate, 1 kg of sodium bisulfite, 2 kg of diisobutylamidine hydrochloride and 2 kg of azobisisobutylamidine hydrochloride (initiator). Polymerize at 70℃ for 4 h to obtain drag reducer C2.

[0041] S3. Preparation of slippery water

[0042] 3 kg of modified nano-silica A2, 0.2 kg of drag reducer C2, and 0.02 kg of C7F were added. 15 CONH(CH2)2NH(NH2)2COONa, 0.05 kg of dodecyl alcohol polyoxyethylene ether, 0.5 kg of poly(dihydroxyethyl(2-hydroxy)propyl)ammonium chloride, and 110 kg of water are mixed to obtain slippery water D2.

[0043] Example 3

[0044] This embodiment prepares a slippery liquid, specifically including the following steps:

[0045] S1. Preparation of modified nano-silica

[0046] 22 kg of nano-silica and 8 kg of trimethoxyhexadecylsilane (modifier) ​​were mixed evenly in 40 kg of ethanol solution (anhydrous ethanol and water were mixed in a weight ratio of 5:1). 2 kg of thionyl chloride (catalyst) was added and stirred continuously for 30 min to mix evenly. Then the temperature was raised to 60 °C and reacted for 6 h. After drying to remove the reactants, modified nano-silica A3 was obtained.

[0047] S2. Preparation of drag-reducing agents

[0048] Weigh 4 kg of octadecyl alcohol polyoxyethylene ether and 5 kg of acryloyl chloride, mix thoroughly, add 60 kg of acetone and mix thoroughly, react at 70°C for 9 h to obtain polymer monomer B3, whose structural formula is:

[0049] Take 80 kg of acrylamide, 35 kg of acrylic acid, 15 kg of 2-acrylamido-2-methylpropanesulfonic acid and 15 kg of polymer monomer B3 and mix them evenly. Add NaOH solution to adjust the pH value to 8.0. Add 1 kg of ammonium persulfate, 1 kg of sodium bisulfite, 1 kg of diisobutylamidine hydrochloride and 1 kg of azobisisobutylamidine hydrochloride (initiator). Polymerize at 60℃ for 3.5 h to obtain drag reducer C3.

[0050] S3. Preparation of slippery water

[0051] 2 kg of modified nano-silica A3, 0.1 kg of drag reducer C3, and 0.015 kg of C7F were added. 15 CONHVH2CH2COONa, 0.03 kg of nonylphenol polyoxyethylene ether, 0.4 kg of poly(dihydroxyethyl(2-hydroxy)propyl)ammonium chloride, and 105 kg of water were mixed to obtain slippery water D3.

[0052] Example 4

[0053] This embodiment prepares a slippery liquid, specifically including the following steps:

[0054] S1. Preparation of modified nano-silica

[0055] 20 kg of nano-silica and 10 kg of triethoxytridecylfluorooctylsilane (modifier) ​​were mixed evenly in 40 kg of ethanol solution (anhydrous ethanol and water were mixed in a weight ratio of 5:1). 2 kg of trifluoromethanesulfonic acid (catalyst) was added, and the mixture was stirred continuously for 30 min to mix evenly. Then the temperature was raised to 70 °C and the reaction was carried out for 6 h. After drying to remove the reactants, modified nano-silica A4 was obtained.

[0056] S2. Preparation of drag-reducing agents

[0057] Weigh 4 kg of octadecyl alcohol polyoxyethylene ether and 6 kg of acryloyl chloride, mix thoroughly, add 50 kg of acetone and mix thoroughly again, react at 60°C for 8 h to obtain polymer monomer B4, whose structural formula is:

[0058] Take 78 kg of acrylamide, 33 kg of acrylic acid, 11 kg of 2-acrylamido-2-methylpropanesulfonic acid and 13 kg of polymer monomer B4 and mix them evenly. Add NaOH solution to adjust the pH value to 8.0. Add 1.5 kg of ammonium persulfate, 0.7 kg of sodium bisulfite, 1.5 kg of diisobutylamidine hydrochloride and 1.3 kg of azovinylpyrazole (initiator). Polymerize at 70℃ for 4 h to obtain drag-reducing agent C4.

[0059] S3. Preparation of slippery water

[0060] 2 kg of modified nano-silica A4, 0.2 kg of drag reducer C4, and 0.01 kg of C7F were added. 15 CONH(CH2)2NH(NH2)COONa, 0.01 kg of dodecyl alcohol polyoxyethylene ether, 0.4 kg of poly(dihydroxyethyl(2-hydroxy)propylammonium chloride) chloride, and 100 kg of water were mixed to obtain slippery water D4.

[0061] Example 5

[0062] This embodiment prepares a slippery liquid, specifically including the following steps:

[0063] S1. Preparation of modified nano-silica

[0064] 20 kg of nano-silica and 8 kg of trimethoxyhexadecylsilane (modifier) ​​were mixed evenly in 40 kg of ethanol solution (anhydrous ethanol and water were mixed in a weight ratio of 5:1). 2 kg of p-toluenesulfonic acid (catalyst) was added and stirred continuously for 30 min to mix evenly. Then the temperature was raised to 70 °C and reacted for 5 h. After drying to remove the reactants, modified nano-silica A5 was obtained.

[0065] S2. Preparation of drag-reducing agents

[0066] Weigh 5 kg of isomeric tridecyl alcohol polyoxyethylene ether and 6 kg of acryloyl chloride, mix thoroughly, add 66 kg of acetone and mix thoroughly, react at 77°C for 8 h to obtain polymer monomer B5, whose structural formula is:

[0067] Take 77 kg of acrylamide, 33 kg of acrylic acid, 11 kg of 2-acrylamido-2-methylpropanesulfonic acid and 11 kg of polymer monomer B5 and mix them evenly. Add NaOH solution to adjust the pH value to 8.0. Add 2 kg of ammonium persulfate, 1 kg of sodium bisulfite, 2 kg of diisobutylamidine hydrochloride and 1 kg of azobisisobutylamidine hydrochloride (initiator). Polymerize at 66℃ for 3 h to obtain drag reducer C5.

[0068] S3. Preparation of slippery water

[0069] 2 kg of modified nano-silica A5, 0.1 kg of drag reducer C5, and 0.01 kg of (C7F) were added. 15 The following ingredients were mixed: CO2)2NHCH2COONa, 0.03 kg of nonylphenol polyoxyethylene ether, 0.4 kg of poly(2-hydroxypropyl)ammonium chloride, and 110 kg of water to obtain slippery water D5.

[0070] Example 6

[0071] This embodiment provides performance testing of slick water (D1-D5) and provides comparative examples to verify the effect, specifically including the following steps:

[0072] I. Sample Preparation

[0073] Samples 1-5 are the slippery waters D1-D5 prepared in Examples 1-5;

[0074] Comparative Sample 1: The preparation method of Comparative Sample 1 is basically the same as that of Example 1. The only difference is that Comparative Sample 1 does not contain modified nano-silica and fluorinated surfactant. The other components, dosages and control parameters are exactly the same as those in Example 1.

[0075] Comparative Sample 2: The preparation method of Comparative Sample 2 is basically the same as that of Example 2. The only difference is that Comparative Sample 2 does not contain modified nano-silica and fluorinated surfactant. The other components, dosages and control parameters are exactly the same as those in Example 2.

[0076] II. Apparent viscosity test

[0077] According to section 7.2 of the "Technical Requirements for Water-Based Fracturing Fluids" (SY / T 7627-2021), the apparent viscosity of samples 1-5, control sample 1, and control sample 2 was tested using a viscosity meter. The results are shown in Table 1.

[0078] Table 1. Results of Apparent Viscosity Test

[0079] Sample number Apparent viscosity / mPa·s Sample 1 35.2 Sample 2 36.6 Sample 3 34.4 Sample 4 35.7 Sample 5 36.2 Comparison Sample 1 33.8 Comparison Sample 2 33.7

[0080] As shown in Table 1, the apparent viscosity of samples 1–5 is 34.4–36.6 mPa·s, while the apparent viscosity of control samples 1 and 2 is 33.8 mPa·s and 33.7 mPa·s, respectively. This indicates that the modified nano-silica and fluorinated surfactants have little effect on the viscosity of the slickwater system, and the addition of modified nano-silica and fluorinated surfactants will not affect the apparent viscosity of the slickwater system.

[0081] III. Contact Angle Test

[0082] Take a 1cm piece of the rock core to be tested 3 The core blocks were completely immersed in samples 1-5, control sample 1, and control sample 2 at 60℃ for 4 days. Then, the core blocks were removed and dried at 40℃ for 2 hours. The contact angle of the water phase on the core surface was measured using a contact angle meter. The results are shown in Table 2.

[0083] Table 2 Contact Angle Test Results

[0084] Sample number Contact angle / ° Original rock core 21 Sample 1 96 Sample 2 115 Sample 3 100 Sample 4 99 Sample 5 105 Comparison Sample 1 30 Comparison Sample 2 25

[0085] As shown in Table 2, the contact angles of samples 1–5 with modified nano-silica and fluorinated surfactants ranged from 96° to 115°, while the contact angle of control sample 1 was only 30° and the contact angle of control sample 2 was only 25°. This indicates that modified nano-silica and fluorinated surfactants can effectively increase the hydrophobicity of the core surface.

[0086] IV. Core Permeability Recovery Rate Test

[0087] Oil was extracted from rock samples and dried at 80℃ for 12 h. The samples were then saturated with standard brine under vacuum for 24 h. The oil phase permeability K1 of the core was measured forward. Samples 1–5, control sample 1, and control sample 2 were used to perform forward contamination on the rock samples (contamination pressure difference 4 MPa, temperature 120℃, time 12 h). The oil phase permeability K2 of the core was then measured forward. The permeability recovery rate of the core was calculated using the following formula. The results are shown in Table 3.

[0088] H = K2 / K1 × 100%

[0089] Table 3. Results of Core Permeability Recovery Rate Test

[0090] Sample number <![CDATA[K1 / 10 -3 μm 2 ]]> <![CDATA[K2 / 10 -3 μm 2 ]]> H / ％ Sample 1 0.51 0.47 92.16 Sample 2 0.86 0.8 93.02 Sample 3 0.76 0.71 93.42 Sample 4 0.56 0.51 91.07 Sample 5 0.49 0.45 91.84 Comparison Sample 1 0.57 0.47 82.46 Comparison Sample 2 0.61 0.5 81.97

[0091] As shown in Table 3, the permeability recovery rates of core samples 1–5 treated with modified nano-silica and fluorinated surfactants ranged from 91.07% to 93.42%, while the permeability recovery rates of core samples 1 and 2 treated with modified nano-silica and fluorinated surfactants were 82.46% and 81.97%, respectively. This indicates that the slickwater system with modified nano-silica and fluorinated surfactants has a good reservoir protection effect.

[0092] V. Resistivity Test

[0093] According to the test methods related to drag reduction in section 7.8 of "SY / T 7627-2021 Technical Requirements for Water-Based Fracturing Fluids", samples 1-5, control sample 1, and control sample 2 were tested respectively. The results are shown in Table 4.

[0094] Table 4. Results of drag reduction test

[0095] Sample number Drag reduction rate / % Sample 1 76.3 Sample 2 73.3 Sample 3 73.2 Sample 4 76.1 Sample 5 75.8 Comparison Sample 1 72.6 Comparison Sample 2 73.8

[0096] As shown in Table 4, the drag reduction rates of samples 1 to 5 with modified nano-silica and fluorinated surfactants ranged from 73.2% to 76.3%, while the drag reduction rate of control sample 1 was 72.6% and that of control sample 2 was 73.8%. This indicates that the drag reduction rate of the slippery water system with modified nano-silica and fluorinated surfactants was improved compared with the control samples.

Claims

1. A type of slippery water, characterized in that, The raw materials used to make it, by weight, include: 1-3 parts modified nano silica, 0.05-0.2 parts drag reducer, 0.01-0.02 parts fluorinated surfactant, 0.01-0.05 parts drainage aid, 0.1-0.5 parts clay stabilizer, and 100-110 parts water.

2. The slippery water according to claim 1, characterized in that, The modified nano-silica is prepared by the following method: 20-25 parts by weight of nano-silica and 5-10 parts by weight of modifier are mixed in an ethanol solution, 1-3 parts by weight of catalyst are added to react, and the modified nano-silica is obtained after drying. The modifier includes perfluorooctyltriethoxysilane, trimethoxyhexadecylsilane, or triethoxytridecylfluorooctylsilane; the catalyst includes p-toluenesulfonic acid, thionyl chloride, or trifluoromethanesulfonic acid.

3. The slippery water according to claim 2, characterized in that, The reaction is carried out at a temperature of 60–80°C for 4–6 hours.

4. The slippery water according to claim 1, characterized in that, The fluorinated surfactant includes (C7F) 15 CO2)2NHCH2COONa、(C7F 15 CONH(CH2)2NH(NH2)2COONa or C7F 15 CONHCH2CH2COONa.

5. The slippery water according to claim 1, characterized in that, The drainage aid includes nonylphenol polyoxyethylene ether or dodecyl alcohol polyoxyethylene ether.

6. The slippery water according to claim 1, characterized in that, The clay stabilizer includes polydihydroxyethyl(2-hydroxy)propylammonium chloride.

7. A slippery water device according to any one of claims 1 to 6, characterized in that, The drag-reducing agent is prepared by the following method: 75-80 parts by weight of acrylamide, 25-35 parts by weight of acrylic acid, 5-15 parts by weight of 2-acrylamide-2-methylpropanesulfonic acid and 10-20 parts by weight of polymer monomer are mixed, the pH value is adjusted to 7-9, 1-2 parts by weight of ammonium persulfate, 0.5-1 parts by weight of sodium bisulfite, 1-2 parts by weight of diisobutylamidine hydrochloride and 1-2 parts by weight of initiator are added, and a polymerization reaction is carried out to obtain the drag-reducing agent; The polymer monomer includes In the formula, n is 8, 10, 12 or 14; m is 8, 10, 12 or 20; The initiator includes azovinylpyrazole or azobisisobutyramidine hydrochloride.

8. A slippery water device according to claim 7, characterized in that, The polymerization reaction is carried out at a temperature of 50–70°C for 3–4 hours.

9. A slippery water device according to claim 7, characterized in that, The polymer monomer is prepared by the following method: 3-5 parts by weight of polyoxyethylene ether compound, 3-6 parts by weight of acryloyl chloride and 50-70 parts by weight of acetone are mixed and reacted at 60-80°C for 8-10 hours to obtain the polymer monomer. The polyoxyethylene ether compounds include octadecyl alcohol polyoxyethylene ether or isotridecyl alcohol polyoxyethylene ether.

10. A method for preparing slippery water according to any one of claims 1 to 9, characterized in that, It is made by mixing drag reducer, fluorinated surfactant, drainage aid, clay stabilizer and water, then adding modified nano-silica and mixing again to obtain slippery water.

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