An emulsion-type fracturing fluid thickener and its preparation method

Abstract

This invention relates to the field of oilfield chemical technology, and proposes an emulsion-type fracturing fluid thickener and its preparation method. The raw materials of the emulsion-type fracturing fluid thickener include the following components in parts by weight: 40-50 parts acrylamide, 30-40 parts acrylic acid, 20-30 parts sodium styrene sulfonate, 10-20 parts methacryloyloxyethyltrimethylammonium chloride, 5-10 parts emulsifier, 5-10 parts stabilizer, 1-2 parts initiator, and 100-120 parts water; the stabilizer includes hydroxyethyl-β-cyclodextrin and chitosan quaternary ammonium salt. This technical solution solves the problem of poor temperature and shear resistance in existing emulsion-type fracturing fluid thickeners.

Description

Technical Field

[0001] This invention relates to the field of oilfield chemical technology, specifically to an emulsion-type fracturing fluid thickener and its preparation method. Background Technology

[0002] Fracturing oil and gas reservoirs with fracturing fluids can increase the seepage area of ​​oil and gas and improve oil and gas production capacity. Traditional fracturing fluids include powdered guar gum and polymer thickeners. This formulation requires a certain swelling time, has poor fluid supply capacity, and is costly, making it unsuitable for large-scale volumetric fracturing.

[0003] Emulsion-type fracturing fluid thickeners can rapidly swell and increase viscosity in a short time, meeting the application requirements of different types of fracturing fluids such as slickwater, linear gels, and gels, and are highly favored by the market. Currently, however, emulsion-type fracturing fluid thickeners have poor temperature and shear resistance. Therefore, developing a novel emulsion-type fracturing fluid thickener is of great significance. Summary of the Invention

[0004] This invention proposes an emulsion-type fracturing fluid thickener and its preparation method, which solves the problem of poor temperature and shear resistance of emulsion-type fracturing fluid thickeners in related technologies.

[0005] The technical solution of the present invention is as follows:

[0006] This invention proposes an emulsion-type fracturing fluid thickener, the raw materials of which include the following components in parts by weight: 40-50 parts acrylamide, 30-40 parts acrylic acid, 20-30 parts sodium styrene sulfonate, 10-20 parts methacryloyloxyethyltrimethylammonium chloride, 5-10 parts emulsifier, 5-10 parts stabilizer, 1-2 parts initiator, and 100-120 parts water;

[0007] The stabilizers include hydroxyethyl-β-cyclodextrin and chitosan quaternary ammonium salt.

[0008] As a further technical solution, the mass ratio of the hydroxyethyl-β-cyclodextrin to the chitosan quaternary ammonium salt is 1:4 to 4:1.

[0009] When the mass ratio of hydroxyethyl-β-cyclodextrin to chitosan quaternary ammonium salt is 1:4 to 4:1, it helps to further improve the temperature and shear resistance of emulsion-type fracturing fluid thickener.

[0010] As a further technical solution, the mass ratio of the hydroxyethyl-β-cyclodextrin to the chitosan quaternary ammonium salt is 3:2.

[0011] When the mass ratio of hydroxyethyl-β-cyclodextrin to chitosan quaternary ammonium salt is 3:2, the emulsion-type fracturing fluid thickener exhibits superior temperature and shear resistance.

[0012] As a further technical solution, the stabilizer also includes poloxamer.

[0013] The addition of poloxamer not only further enhances the stability of the spatial network structure in emulsion fracturing fluid thickeners, but also inhibits the influence of metal ions on the stability of emulsion fracturing fluid thickeners, thereby further enhancing the temperature and shear resistance of emulsion fracturing fluid thickeners.

[0014] As a further technical solution, the mass ratio of the hydroxyethyl-β-cyclodextrin and chitosan quaternary ammonium salt to the poloxamer is 3:2.

[0015] When the mass ratio of hydroxyethyl-β-cyclodextrin and chitosan quaternary ammonium salt to poloxamer is 3:2, the temperature and shear resistance of the emulsion-type fracturing fluid thickener can be further improved.

[0016] As a further technical solution, the emulsifier is one or more of fatty alcohol polyoxyethylene ether, sodium dodecylbenzene sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate.

[0017] As a further technical solution, the initiator is one or more of azobisisobutyronitrile, benzoyl peroxide, and dimethyl azobisisobutyrate.

[0018] As a further technical solution, the raw materials also include 10 to 20 parts by weight of an organic solvent;

[0019] The organic solvent is one or more of toluene, o-xylene, and cyclohexane.

[0020] The addition of organic solvents can promote the formation of reverse micelles in emulsion-type fracturing fluid thickeners, thereby improving the thermal stability of emulsion-type fracturing fluid thickeners.

[0021] This invention also proposes a method for preparing the emulsion-type fracturing fluid thickener, comprising the following steps:

[0022] S1. Add acrylamide, acrylic acid, sodium styrene sulfonate and methacryloyloxyethyltrimethylammonium chloride to water and mix well to obtain mixture A;

[0023] S2. Add the remaining components to the mixture A and react to obtain an emulsion-type fracturing fluid thickener.

[0024] As a further technical solution, in step S2, the reaction is carried out at a temperature of 70~80℃ for 2~3 hours.

[0025] The working principle and beneficial effects of this invention are as follows:

[0026] 1. In this invention, the stabilizers include hydroxyethyl-β-cyclodextrin and chitosan quaternary ammonium salt. Through the synergistic effect of the two, the stability of the spatial network structure in the emulsion fracturing fluid thickener is enhanced, so that the emulsion fracturing fluid thickener still has good viscosity at higher temperatures, thereby improving the temperature and shear resistance of the emulsion fracturing fluid thickener. Detailed Implementation

[0027] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] In the following examples and comparative examples, unless otherwise specified, the purity of acrylamide is 99%, the purity of acrylic acid is 95%, the purity of sodium styrene sulfonate is 99%, the purity of methacryloyloxyethyltrimethylammonium chloride is 98%, the purity of sodium dodecylbenzene sulfonate is 99%, the purity of hydroxyethyl-β-cyclodextrin is 99%, the degree of substitution of chitosan quaternary ammonium salt is 90%, the type of poloxamer is poloxamer 188, the purity of azobisisobutyronitrile is 99%, and the purity of toluene is 99.8%.

[0029] Example 1

[0030] A method for preparing an emulsion-type fracturing fluid thickener includes the following steps:

[0031] S1. By weight, add 40 parts acrylamide, 30 parts acrylic acid, 20 parts sodium styrene sulfonate and 10 parts methacryloyloxyethyltrimethylammonium chloride to 100 parts water and mix well to obtain mixture A.

[0032] S2. By weight, add 5 parts sodium dodecylbenzenesulfonate, 5 parts stabilizer, and 1 part azobisisobutyronitrile to mixture A, mix evenly, and react at 70°C for 3 hours to obtain emulsion-type fracturing fluid thickener.

[0033] The stabilizer consists of 0.5 parts hydroxyethyl-β-cyclodextrin and 4.5 parts chitosan quaternary ammonium salt.

[0034] Example 2

[0035] A method for preparing an emulsion-type fracturing fluid thickener includes the following steps:

[0036] S1. By weight, add 50 parts acrylamide, 40 parts acrylic acid, 30 parts sodium styrene sulfonate and 20 parts methacryloyloxyethyltrimethylammonium chloride to 120 parts water and mix well to obtain mixture A.

[0037] S2. By weight, add 10 parts sodium dodecylbenzenesulfonate, 10 parts stabilizer, and 2 parts azobisisobutyronitrile to mixture A, mix well, and react at 80°C for 2 hours to obtain emulsion-type fracturing fluid thickener.

[0038] The stabilizer consists of 0.5 parts hydroxyethyl-β-cyclodextrin and 9.5 parts chitosan quaternary ammonium salt.

[0039] Example 3

[0040] The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the stabilizer consists of 9.5 parts of hydroxyethyl-β-cyclodextrin and 0.5 parts of chitosan quaternary ammonium salt.

[0041] Example 4

[0042] The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the stabilizer consists of 2 parts of hydroxyethyl-β-cyclodextrin and 8 parts of chitosan quaternary ammonium salt.

[0043] Example 5

[0044] The only difference between this embodiment and Embodiment 2 is that in this embodiment, the stabilizer consists of 8 parts of hydroxyethyl-β-cyclodextrin and 2 parts of chitosan quaternary ammonium salt.

[0045] Example 6

[0046] The only difference between this embodiment and Embodiment 2 is that, in this embodiment, the stabilizer consists of 6 parts of hydroxyethyl-β-cyclodextrin and 4 parts of chitosan quaternary ammonium salt.

[0047] Example 7

[0048] The only difference between this embodiment and Example 6 is that in this embodiment, the stabilizer consists of 4.8 parts of hydroxyethyl-β-cyclodextrin, 3.2 parts of chitosan quaternary ammonium salt, and 2 parts of poloxamer.

[0049] Example 8

[0050] The only difference between this embodiment and Example 6 is that in this embodiment, the stabilizer consists of 3 parts hydroxyethyl-β-cyclodextrin, 2 parts chitosan quaternary ammonium salt, and 5 parts poloxamer.

[0051] Example 9

[0052] The only difference between this embodiment and Example 6 is that in this embodiment, the stabilizer consists of 3.6 parts of hydroxyethyl-β-cyclodextrin, 2.4 parts of chitosan quaternary ammonium salt, and 4 parts of poloxamer.

[0053] Example 10

[0054] The only difference between this embodiment and embodiment 9 is that in step S2 of this embodiment, 15 parts of toluene are added to mixture A.

[0055] Comparative Example 1

[0056] The only difference between this comparative example and Example 1 is that in this comparative example, the stabilizer is 5 parts of hydroxyethyl-β-cyclodextrin.

[0057] Comparative Example 2

[0058] The only difference between this comparative example and Example 1 is that in this comparative example, the stabilizer is 5 parts of chitosan quaternary ammonium salt.

[0059] Comparative Example 3

[0060] The only difference between this comparative example and Example 1 is that no stabilizer was added in this comparative example.

[0061] Experimental Example 1: Temperature and Shear Resistance Test

[0062] Thirteen blank solutions (water) were numbered 1 to 13. The emulsion-type fracturing fluid thickeners prepared in Examples 1-10 and Comparative Examples 1-3 were added to each blank solution (the mass ratio of emulsion-type fracturing fluid thickener to blank solution was 6:1000). The temperature and shear resistance of the emulsion-type fracturing fluid thickeners were tested at 90℃ and 110℃ according to SY / T 5107-2016 "Performance Evaluation Method for Water-Based Fracturing Fluids". The shear rate at 90℃ was 675 s⁻¹. -1 The shearing time was 2.5 min, and the shearing rate at 110℃ was 1350 s. -1 The shearing time was 5 minutes. The test results are shown in Table 1 below.

[0063] Table 1. Test results of temperature and shear resistance.

[0064]

[0065] As can be seen from the comparison between Example 1 and Comparative Examples 1-3, the synergistic effect of hydroxyethyl-β-cyclodextrin and chitosan quaternary ammonium salt can significantly improve the temperature and shear resistance of emulsion-type fracturing fluid thickener.

[0066] A comparison of Examples 2-3 with Examples 4-6 shows that a mass ratio of hydroxyethyl-β-cyclodextrin to chitosan quaternary ammonium salt of 1:4 to 4:1 helps to further improve the temperature and shear resistance of the emulsion-type fracturing fluid thickener. A comparison of Example 6 with Examples 4-5 shows that the optimal mass ratio of hydroxyethyl-β-cyclodextrin to chitosan quaternary ammonium salt is 3:2. A comparison of Example 6 with Examples 7-9 shows that the addition of poloxamer to the stabilizer can further enhance the temperature and shear resistance of the emulsion-type fracturing fluid thickener. A comparison of Example 9 with Examples 7-8 shows that a mass ratio of hydroxyethyl-β-cyclodextrin to chitosan quaternary ammonium salt and poloxamer of 3:2 can further improve the temperature and shear resistance of the emulsion-type fracturing fluid thickener. A comparison of Example 9 with Example 10 shows that the addition of organic solvents further improves the temperature and shear resistance of the emulsion-type fracturing fluid thickener.

[0067] Application Example 1

[0068] The emulsion-type fracturing fluid thickener prepared in Example 10 was used to formulate a slickwater fracturing fluid (the fracturing fluid consisted of 0.1% low-viscosity slickwater thickener and 0.6% high-viscosity slickwater thickener) according to the designed formula. This fracturing fluid was applied to a shale oil well in the eastern Junggar Basin (the target layer was at a depth of 3813.6 m in the middle, the average reservoir thickness was 7 m, and the reservoir temperature was 102 °C). The maximum operating pressure was 72 MPa, and the operating flow rate was 15.5 m³ / h. 2 / min. Construction results show that the entire construction process went smoothly, the construction pressure was stable, and the highest sand ratio was 26%.

[0069] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thickener for emulsion-type fracturing fluid, characterized in that, The raw materials include the following components in parts by weight: 40-50 parts acrylamide, 30-40 parts acrylic acid, 20-30 parts sodium styrene sulfonate, 10-20 parts methacryloyloxyethyltrimethylammonium chloride, 5-10 parts emulsifier, 5-10 parts stabilizer, 1-2 parts initiator, and 100-120 parts water. The stabilizer comprises hydroxyethyl-β-cyclodextrin and chitosan quaternary ammonium salt in a mass ratio of 1:4 to 4:

1.

2. The emulsion-type fracturing fluid thickener according to claim 1, characterized in that, The mass ratio of the hydroxyethyl-β-cyclodextrin to the chitosan quaternary ammonium salt is 3:

2.

3. The emulsion-type fracturing fluid thickener according to claim 1, characterized in that, The stabilizer also includes poloxamer.

4. The emulsion-type fracturing fluid thickener according to claim 3, characterized in that, The mass ratio of the hydroxyethyl-β-cyclodextrin and chitosan quaternary ammonium salt to the poloxamer is 3:

2.

5. The emulsion-type fracturing fluid thickener according to claim 1, characterized in that, The emulsifier is one or more of fatty alcohol polyoxyethylene ether, sodium dodecylbenzene sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate.

6. The emulsion-type fracturing fluid thickener according to claim 1, characterized in that, The initiator is one or more of azobisisobutyronitrile, benzoyl peroxide, and dimethyl azobisisobutyrate.

7. The emulsion-type fracturing fluid thickener according to claim 1, characterized in that, The raw materials also include 10 to 20 parts by weight of organic solvent; The organic solvent is one or more of toluene, o-xylene, and cyclohexane.

8. A method for preparing an emulsion-type fracturing fluid thickener as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Add acrylamide, acrylic acid, sodium styrene sulfonate and methacryloyloxyethyltrimethylammonium chloride to water and mix well to obtain mixture A; S2. Add the remaining components to the mixture A, mix evenly, and react to obtain an emulsion-type fracturing fluid thickener.

9. The method for preparing an emulsion-type fracturing fluid thickener according to claim 8, characterized in that, In step S2, the reaction is carried out at a temperature of 70-80°C for 2-3 hours.

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