Polycationic surfactant FCWS, preparation method and application

Abstract

The invention discloses a polycationic surfactant FCWS as well as a preparation method and application thereof, and belongs to the technical field of oilfield chemical assistants. The preparation method comprises the following steps: S1, dissolving 1, 5-diaminopentane in ethanol, adding epoxy chloropropane, and reacting at 25 DEG C for 24 hours to obtain an ethanol solution of an intermediate A; s2, an ethanol solution of the intermediate A and a dimethyl tertiary amine organic matter react for 36-48 h at the temperature of 80 DEG C, and the polycationic surface active agent FCWS is obtained. According to the invention, the prepared polycationic surfactant is adopted to modify the proppant, the settling velocity of the proppant is reduced, the proppant with excellent suspension capacity is obtained, and the proppant with excellent performance is provided for a reservoir yield-increasing transformation technology. The method is suitable for modifying the silicon dioxide-containing proppant.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemical additives technology, and relates to a modified proppant, specifically a multi-cationic surfactant FCWS, its preparation method and application. Background Technology

[0002] With the large-scale exploitation and consumption of conventional oil and gas reservoirs, unconventional oil and gas resources such as tight sandstone gas, coalbed methane, and shale gas, characterized by low permeability, ultra-low permeability, and deep, high-temperature formations, urgently need to be developed and utilized. Hydraulic fracturing is a key technology for enhancing oil and gas reservoir production. During hydraulic fracturing, proppant is transported into artificial fractures using fracturing fluid to prevent fracture closure after the operation. The migration and placement morphology of the proppant in the fracture largely determine the effectiveness of the fracturing operation: the greater the depth of proppant penetration into the fracture, the greater the effective length of the fracture support, the larger the volume of reservoir connected, and the better the improvement effect; the more uniform the proppant placement in the fracture, the better the fracture conductivity, and the more conducive it is to achieving high production in oil and gas wells. The key factors affecting the migration and placement morphology of proppant in the fracture are the proppant's suspension capacity and settling velocity. Props with strong suspension capacity settle more slowly in the fracturing fluid, can migrate to deeper fractures, and have a more uniform placement morphology. Therefore, settling velocity is an important reference performance for evaluating proppant performance. Currently available proppants have the problem of relatively fast settling velocity, so there is an urgent need for proppants with excellent performance.

[0003] Surfactants are amphiphilic small molecule compounds that possess both hydrophilic and hydrophobic groups. Due to their amphiphilic nature, they are often used to modify fluid properties. Cationic surfactants, with their positively charged groups, can adsorb onto proppants, thereby modifying the proppant. The modifying ability of a surfactant on a proppant is directly proportional to the number of its cations. Ordinary surfactants typically have only 1-2 cations, resulting in poor modification effects. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-cationic surfactant FCWS, its preparation method, and its application, in order to solve the problem of poor performance of surfactant-modified proppant in the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A multi-cationic surfactant FCWS has the following structural formula:

[0007]

[0008] Wherein, R is erucamide propane, hexadecane, octadecane, or docosane.

[0009] This invention also provides a method for preparing the above-mentioned multi-cationic surfactant FCWS, comprising the following steps performed sequentially:

[0010] S1. Dissolve 1,5-diaminopentane in ethanol, add epichlorohydrin, and react at 25°C for 24 h to obtain an ethanol solution of intermediate A;

[0011] The reaction formula is:

[0012]

[0013] S2. An ethanol solution of intermediate A and a dimethyl tertiary amine organic compound are reacted at 80°C for 36–48 h to obtain the polycationic surfactant FCWS.

[0014] The reaction formula is:

[0015]

[0016] In the formula, R is erucamide propane, hexadecane, octadecane, or docosane.

[0017] As a limitation, the dimethyl tertiary amine organic compounds include erucamide propyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine, octadecyl dimethyl tertiary amine, or docosyl dimethyl tertiary amine.

[0018] As another limitation, the molar ratio of 1,5-diaminopentane to epichlorohydrin is 1:4 to 4.2; and the molar ratio of intermediate A to dimethyl tertiary amine organic compound is 1:4.5 to 5.

[0019] The present invention also provides an application of the aforementioned multi-cationic surfactant FCWS, wherein the multi-cationic surfactant FCWS is used to modify a proppant.

[0020] As a limitation, the proppant includes quartz sand or ceramsite.

[0021] As another limitation, the modified proppant specifically includes: dispersing the proppant in water, adding 5 wt% of the multi-cationic surfactant FCWS to the proppant, stirring at 20-80°C for 1-3 hours, precipitating, filtering, and drying to obtain the modified proppant.

[0022] As a further limitation, the stirring speed is 10000 r / min; the sedimentation time is 6 h; and the drying temperature is 55℃.

[0023] By adopting the above technical solution, the technical progress achieved by this invention compared with the prior art is as follows:

[0024] ① The present invention provides a multi-cationic surfactant FCWS, which has both hydrophilic and hydrophobic groups, can change fluid properties, has 4 cations, can adsorb silica on the surface of the proppant, and has a better modification effect on silica-containing proppants (such as quartz sand or ceramsite).

[0025] ② The present invention provides a method for preparing a multi-cationic surfactant FCWS, which has high yield, low cost, and simple production process, and is suitable for industrial production;

[0026] ③ The present invention provides an application of a multi-cationic surfactant FCWS to prepare a modified proppant, which has strong suspension ability and low settling rate, thereby spreading more evenly in the fracturing fracture and giving the fracture good conductivity, meeting the requirements of fracturing operation.

[0027] This invention uses a prepared multi-cationic surfactant to modify quartz sand proppant, reducing the settling velocity of the proppant and obtaining a proppant with excellent suspension ability, thus providing a high-performance proppant for reservoir enhancement and stimulation technology. Attached Figure Description

[0028] Figure 1 The graph shows the settling velocity of the modified quartz sand proppant prepared under different reaction temperature conditions in Example 8.

[0029] Figure 2 The graph shows the settling velocity of the modified quartz sand proppant prepared under different reaction time conditions in Example 8.

[0030] Figure 3 The image shows the contact angle test results of the quartz sand proppant before modification in Example 8.

[0031] Figure 4 The image shows the contact angle test results of the modified quartz sand proppant in Example 8. Detailed Implementation

[0032] 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.

[0033] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art.

[0034] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0035] Example 1

[0036] This embodiment discloses a multi-cationic surfactant FCWS, the structural formula of which is:

[0037]

[0038] Wherein, R is erucamide propane, hexadecane, octadecane, or docosane.

[0039] Example 2

[0040] This embodiment prepares a multi-cationic surfactant FCWS, specifically including the following steps performed sequentially:

[0041] S1. Dissolve 1,5-diaminopentane in ethanol, and slowly add epichlorohydrin dropwise at a molar ratio of 1:4.2. React at 25°C for 24 hours to obtain a pale yellow liquid, which is an ethanol solution of intermediate A.

[0042] S2. The ethanol solution of intermediate A was heated to 80°C, and erucamide propyl dimethyl tertiary amine (molar ratio of intermediate A to erucamide propyl dimethyl tertiary amine was 1:5) was added dropwise through a constant pressure funnel. The reaction was carried out for 36 hours. After the reaction was completed, the mixture was cooled and the ethanol was removed by rotary evaporation. The mixture was filtered to obtain a pale yellow paste. Acetone was then added and the paste was soaked for 1 day. The product was washed and dried under vacuum to constant weight to obtain the multi-cationic surfactant FCWS. The yield was calculated to be 83%.

[0043] Example 3

[0044] This embodiment prepares a multi-cationic surfactant FCWS, specifically including the following steps performed sequentially:

[0045] S1. Dissolve 1,5-diaminopentane in ethanol, and slowly add epichlorohydrin dropwise at a molar ratio of 1:4.2. React at 25°C for 24 hours to obtain a pale yellow liquid, which is an ethanol solution of intermediate A.

[0046] S2. The ethanol solution of intermediate A was heated to 80°C, and erucamide propyl dimethyl tertiary amine (molar ratio of intermediate A to erucamide propyl dimethyl tertiary amine was 1:5) was added dropwise through a constant pressure funnel. The reaction was carried out for 40 h. After the reaction was completed, the mixture was cooled and the ethanol was removed by rotary evaporation. The mixture was filtered to obtain a pale yellow paste. Acetone was then added and the paste was soaked for 1 day. The product was washed and dried under vacuum to constant weight to obtain the multi-cationic surfactant FCWS. The yield was calculated to be 86%.

[0047] Example 4

[0048] This embodiment prepares a multi-cationic surfactant FCWS, specifically including the following steps performed sequentially:

[0049] S1. Dissolve 1,5-diaminopentane in ethanol, and slowly add epichlorohydrin dropwise at a molar ratio of 1:4.2. React at 25°C for 24 hours to obtain a pale yellow liquid, which is an ethanol solution of intermediate A.

[0050] S2. The ethanol solution of intermediate A was heated to 80°C, and erucamide propyl dimethyl tertiary amine (molar ratio of intermediate A to erucamide propyl dimethyl tertiary amine was 1:5) was added dropwise through a constant pressure funnel. The reaction was carried out for 44 hours. After the reaction was completed, the mixture was cooled and the ethanol was removed by rotary evaporation. The mixture was filtered to obtain a pale yellow paste. Acetone was then added and the paste was soaked for 1 day. The product was washed and dried under vacuum to constant weight to obtain the multi-cationic surfactant FCWS. The yield was calculated to be 91%.

[0051] Example 5

[0052] This embodiment prepares a multi-cationic surfactant FCWS, specifically including the following steps performed sequentially:

[0053] S1. Dissolve 1,5-diaminopentane in ethanol, and slowly add epichlorohydrin dropwise at a molar ratio of 1:4.2. React at 25°C for 24 hours to obtain a pale yellow liquid, which is an ethanol solution of intermediate A.

[0054] S2. The ethanol solution of intermediate A was heated to 80°C, and erucamide propyl dimethyl tertiary amine (molar ratio of intermediate A to erucamide propyl dimethyl tertiary amine was 1:5) was added dropwise through a constant pressure funnel. The reaction was carried out for 48 hours. After the reaction was completed, the mixture was cooled and the ethanol was removed by rotary evaporation. The mixture was then filtered to obtain a pale yellow paste. Acetone was added and the paste was soaked for 1 day. The product was washed and dried under vacuum to constant weight to obtain the multi-cationic surfactant FCWS. The yield was calculated to be 93%.

[0055] Example 6

[0056] This embodiment prepares a multi-cationic surfactant FCWS, specifically including the following steps performed sequentially:

[0057] S1. Dissolve 1,5-diaminopentane in ethanol, and slowly add epichlorohydrin dropwise at a molar ratio of 1:4. React at 25°C for 24 hours to obtain a pale yellow liquid, which is an ethanol solution of intermediate A.

[0058] S2. The ethanol solution of intermediate A was heated to 80°C, and docosyldimethyl tertiary amine (molar ratio of intermediate A to docosyldimethyl tertiary amine was 1:4.5) was added dropwise through a constant pressure funnel. The reaction was carried out for 48 hours. After the reaction was completed, the mixture was cooled and the ethanol was removed by rotary evaporation. The mixture was filtered to obtain a pale yellow paste. Acetone was then added and the paste was soaked for 1 day. The product was washed and dried under vacuum to constant weight to obtain the multi-cationic surfactant FCWS. The yield was calculated to be 88%.

[0059] Example 7

[0060] This embodiment prepares a multi-cationic surfactant FCWS, specifically including the following steps performed sequentially:

[0061] S1. Dissolve 1,5-diaminopentane in ethanol, and slowly add epichlorohydrin dropwise at a molar ratio of 1:4.1. React at 25°C for 24 hours to obtain a pale yellow liquid, which is an ethanol solution of intermediate A.

[0062] S2. The ethanol solution of intermediate A was heated to 80°C, and octadecyl dimethyl tertiary amine (molar ratio of intermediate A to octadecyl dimethyl tertiary amine was 1:4.8) was added dropwise through a constant pressure funnel. The reaction was carried out for 48 hours. After the reaction was completed, the mixture was cooled and the ethanol was removed by rotary evaporation. The mixture was filtered to obtain a pale yellow paste. Acetone was then added and the paste was soaked for 1 day. The product was washed and dried under vacuum to constant weight to obtain the multi-cationic surfactant FCWS. The yield was calculated to be 90%.

[0063] Example 8

[0064] This embodiment discloses the application of the multi-cationic surfactant FCWS, which is applied to a modified quartz sand proppant, and the relevant properties of the modified quartz sand proppant are tested, specifically including:

[0065] S1. Preparation of modified quartz sand

[0066] 20g of quartz sand was dispersed in 500mL of deionized water, and 1g of the multi-cationic surfactant FCWS prepared in Example 7 (accounting for 5wt% of the proppant) was added. The mixture was stirred at a constant speed of 10000r / min for 180min in water baths at different temperatures (20℃, 30℃, 40℃, 50℃, 60℃, 70℃ or 80℃). The mixture was then allowed to stand at room temperature for 6h to precipitate, filtered and dried, and then dried at 55℃ to obtain the modified quartz sand proppant α1-α7.

[0067] 20g of quartz sand was dispersed in 500mL of deionized water, and 1g of the multi-cationic surfactant FCWS prepared in Example 7 (accounting for 5wt% of the proppant) was added. The mixture was stirred at a constant speed of 10000r / min for different times (60min, 80min, 100min, 120min, 140min, 160min, 180min) in a water bath at 60℃. The mixture was then allowed to stand at room temperature for 6h to precipitate, filtered and dried, and then dried at 55℃ to obtain the modified quartz sand proppant α8-α14.

[0068] S2. Effect of modified quartz sand suspension capacity

[0069] A polymer aqueous solution with a viscosity of 6 mPa·s was prepared using a drag-reducing agent polymer (purchased from Chengdu Kelong Chemical Reagent Factory). Modified quartz sand proppant α1-α14 was mixed with the polymer aqueous solution at a mass ratio of 1:10, and then added to a 50 mL graduated cylinder. The time required for the modified quartz sand to settle to the bottom was observed, and the settling velocity was calculated to evaluate the effect of surface modification reaction conditions on the suspension capacity of quartz sand. The results are as follows: Figure 1 and Figure 2 As shown;

[0070] Depend on Figure 1 It can be seen that the optimal reaction temperature for the surfactant FCWS to modify quartz sand is 60℃;

[0071] Depend on Figure 2 It can be seen that the optimal reaction time for the surfactant FCWS to modify quartz sand is 2 hours.

[0072] S3. Effect of modified quartz sand on zeta potential

[0073] Modified silica sand proppant α11 and unmodified silica sand proppant were used. The Zeta potential of the silica sand proppant before and after modification was measured using a Zeta PALS190P l us fully automatic interfacial potential analyzer. The experimental results are shown in Table 2.

[0074] Table 2. Zeta potentials of the quartz sand proppant before and after modification.

[0075] Sample Name Before modification After modification Zeta potential (mV) -31.2 -58.4

[0076] As shown in Table 2, the adsorption of the multi-cationic surfactant FCWS on the surface of quartz sand leads to more exposure of quartz sand crystals, thereby increasing the zeta potential of negatively charged minerals. This indicates that the multi-cationic surfactant FCWS has an excellent modification effect on quartz sand.

[0077] S4. Effect of modified quartz sand on hydrophilicity

[0078] Modified quartz sand proppant α11 and unmodified quartz sand proppant were respectively pressed into smooth, clean, and measurable solid sheets. The contact angle between the quartz sheet surface and water was measured using a fully automatic contact angle meter. The experimental results are as follows: Figure 3 and Figure 4 As shown;

[0079] Depend on Figure 3 and Figure 4 It can be seen that the contact angle of the quartz sand flakes in the aqueous phase before modification was 56.055°, while that after modification was 89.047°, an increase of 32.992°. The hydrophilicity was significantly reduced, indicating that the modification with the multi-cationic surfactant FCWS can significantly change the hydrophilicity of quartz sand, thereby significantly improving the suspension ability of the proppant in slickwater, enabling the proppant to migrate to the far end of the fracture and improving the fracturing effect.

Claims

1. A multi-cationic surfactant FCWS, characterized in that, Its structural formula is: Wherein, R is erucamide propane, hexadecane, octadecane, or docosane.

2. The method for preparing a multi-cationic surfactant FCWS according to claim 1, characterized in that, This includes the following steps performed sequentially: S1. Dissolve 1,5-diaminopentane in ethanol, add epichlorohydrin, and react at 25°C for 24 h to obtain an ethanol solution of intermediate A; S2. An ethanol solution of intermediate A and a dimethyl tertiary amine organic compound are reacted at 80°C for 36–48 h to obtain the polycationic surfactant FCWS.

3. The preparation method according to claim 2, characterized in that, The dimethyl tertiary amine organic compounds include erucamide propyl dimethyl tertiary amine, hexadecyl dimethyl tertiary amine, octadecyl dimethyl tertiary amine, or docosyl dimethyl tertiary amine.

4. The preparation method according to claim 2 or 3, characterized in that, The molar ratio of 1,5-diaminopentane to epichlorohydrin is 1:4 to 4.2; the molar ratio of intermediate A to dimethyl tertiary amine organic compound is 1:4.5 to 5.

5. The application of the multi-cationic surfactant FCWS according to claim 1, characterized in that, The multi-cationic surfactant FCWS is used to modify the proppant.

6. The application according to claim 5, characterized in that, The proppant includes quartz sand or ceramsite.

7. The application according to claim 5 or 6, characterized in that, The modified proppant specifically comprises: dispersing the proppant in water, adding 5 wt% of the multi-cationic surfactant FCWS to the proppant, stirring at 20–80°C for 1–3 h, precipitating, filtering, and drying to obtain the modified proppant.

8. The application according to claim 7, characterized in that, The stirring speed is 10000 r / min; the sedimentation time is 6 h; and the drying temperature is 55℃.

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