Modified biogel fracturing fluid thickening agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of oil-gas field development, in particular to a modified biogel fracturing fluid thickening agent as well as a preparation method and application thereof, and the biogel fracturing fluid thickening agent is prepared by polymerizing a water-phase mixed solution and an oil-phase mixed solution; wherein the water-phase mixed solution is prepared by mixing the following components in parts by weight: 10 to 20 parts of acrylamide, 10 to 15 parts of methacryloyloxyethyl dimethyl sodium p-benzenesulfonate ammonium chloride, 5 to 8 parts of bis (dodecyl amide) ethylene and 60 parts of water; the oil-phase mixed solution is prepared by mixing 4-8 parts by weight of an emulsifier and 35-45 parts by weight of white oil; the preparation method comprises the following steps: uniformly mixing an oil-phase mixed solution and a water-phase mixed solution, and reacting at 45-65 DEG C for 2-4 hours under the catalysis of azobis (isobutylamidine hydrochloride), the modified biogel fracturing fluid thickener can realize hydrophobic association tackifying in water, has the functions of viscosity change, swelling prevention, resistance reduction and the like, is low in residue, small in damage and good in temperature resistance and shear resistance, and meets the construction requirements.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a modified bio-gel fracturing fluid thickener, a preparation method thereof and application thereof. Background Art

[0002] Fracturing fluid is a working fluid used for hydraulic fracturing of oil and gas layers, and plays an important role in oil and gas well production increase measures. With the deepening of exploration and development of unconventional oil and gas resources, the functional requirements for fracturing fluid are getting higher and higher. Bio-gel fracturing fluid has attracted more and more attention and has been widely used due to its online mixing, cleanliness, and low damage performance. CN113549443A, CN108048067A, etc. disclose a bio-gel thickener, but it lacks multiple functions such as drag reduction and sand carrying, and the viscosity-changing effect is poor. Summary of the invention

[0003] The purpose of the present invention is to provide a modified bio-gel fracturing fluid thickener, a preparation method and an application thereof. The modified bio-gel fracturing fluid thickener is obtained by inverse emulsion copolymerization, and has the functions of reducing resistance, changing viscosity, preventing swelling, carrying sand, etc., and solves the problem that the current bio-gel fracturing fluid thickener has poor viscosity changing effect.

[0004] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0005] In a first aspect, the present invention provides a modified bio-gel fracturing fluid thickener, wherein the modified bio-gel fracturing fluid thickener is prepared by polymerizing a water phase mixed liquid and an oil phase mixed liquid;

[0006] The components of the aqueous phase mixed liquid include: by weight, 10-20 parts of acrylamide, 10-15 parts of sodium methacryloyloxyethyl dimethyl benzenesulfonate ammonium chloride, 5-8 parts of bis(dodecylamide)ethylene and 60 parts of water;

[0007] The components of the oil phase mixed liquid include: by weight, 4-8 parts of emulsifier and 35-45 parts of white oil.

[0008] The specific chemical structure of the modified bio-gel fracturing fluid thickener is as follows:

[0009] Preferably, the emulsifier is a mixture of span-60 and tween-60.

[0010] More preferably, the weight ratio of span-60 to tween-60 is 1:(0.3-0.5).

[0011] In a second aspect, the present invention provides a method for preparing the modified bio-gel fracturing fluid thickener, comprising the following steps:

[0012] S1, mixing acrylamide, sodium methacryloyloxyethyl dimethyl benzenesulfonate ammonium chloride, bis(dodecylamide)ethylene and water to obtain an aqueous phase mixture;

[0013] S2, mixing the emulsifier and the white oil evenly to obtain an oil phase mixed liquid;

[0014] S3, uniformly mixing the oil phase mixed liquid and the water phase mixed liquid, and heating; dropping azobisisobutylamidine hydrochloride into the reaction mixed liquid, and continuing the reaction to obtain a modified bio-gel fracturing fluid thickener.

[0015] Preferably, in step S3, the oil phase mixed liquid and the water phase mixed liquid are uniformly mixed, nitrogen is passed through the mixed liquid to deoxygenate the mixed liquid under stirring conditions, and the mixed liquid is heated to 45° C.-65° C.

[0016] Preferably, in step S3, 0.02 wt. % to 0.035 wt. % of azobisisobutyramidine hydrochloride is added dropwise to the reaction mixture based on the total weight of acrylamide, sodium methacryloyloxyethyl dimethylbenzenesulfonate ammonium chloride and bis(dodecylamide)ethylene.

[0017] Preferably, in step S3, azobisisobutylamidine hydrochloride is added dropwise to the reaction mixture, and the reaction is continued by keeping the temperature for 2h-4h.

[0018] In a third aspect, the present invention provides an application of the modified biogel fracturing fluid thickener in hydraulic fracturing modification.

[0019] Based on the above technical solutions, the technical effects that can be achieved by the present invention are:

[0020] Compared with the existing technology, the modified bio-gel fracturing fluid thickener can achieve hydrophobic association and viscosity increase in water, and has the functions of reducing resistance, changing viscosity, preventing swelling, and carrying sand. It has low residue, little damage, good temperature and shear resistance, and meets construction requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 The graph is a graph showing the viscosity of the modified bio-gel fracturing fluid thickener of Examples 1-5 of the present invention after being mixed with water in different proportions as a function of the added amount;

[0023] Figure 2This is a static sand suspension effect diagram of the modified bio-gel fracturing fluid thickener of Example 4 of the present invention after the sand is suspended for two hours;

[0024] Figure 3 This is the heat and shear resistance rheology diagram of Example 3;

[0025] Figure 4 This is the temperature and shear resistance rheology diagram of the comparative example. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments.

[0027] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0028] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0029] Example 1

[0030] A modified bio-gel fracturing fluid thickener is prepared by the following preparation method:

[0031] S1, 10 parts by weight of acrylamide, 10 parts by weight of methacryloyloxyethyl dimethyl benzenesulfonate sodium ammonium chloride, 5 parts by weight of bis(dodecylamide)ethylene and 60 parts by weight of water were mixed and stirred to obtain an aqueous phase mixture;

[0032] S2, 4 parts by weight of an emulsifier and 35 parts by weight of white oil were mixed uniformly to obtain an oil phase mixture; wherein the emulsifier was a mixture of span-60 and tween-60, and the weight ratio of the two was 1:0.3;

[0033] S3. The oil phase mixed liquid and the water phase mixed liquid are uniformly mixed, nitrogen is passed through the mixed liquid for deoxygenation under stirring conditions, and the mixture is heated to 45°C. Azobisisobutyramidine hydrochloride is added dropwise at a concentration of 0.02 wt.% based on the total weight of acrylamide, sodium methacryloyloxyethyl dimethyl ammonium chloride and bis(dodecylamide)ethylene, and the reaction is continued at the temperature for 3 hours to obtain a modified bio-glue fracturing fluid thickener.

[0034] Example 2

[0035] A modified bio-gel fracturing fluid thickener is prepared by the following preparation method:

[0036] S1, 14 parts by weight of acrylamide, 15 parts by weight of methacryloyloxyethyl dimethyl benzenesulfonate sodium ammonium chloride, 8 parts by weight of bis(dodecylamide)ethylene and 60 parts by weight of water were mixed and stirred to obtain an aqueous phase mixture;

[0037] S2, 5 parts by weight of an emulsifier and 40 parts by weight of white oil are mixed uniformly to obtain an oil phase mixture; wherein the emulsifier is a mixture of span-60 and tween-60, and the weight ratio of the two is 1:0.4;

[0038] S3. The oil phase mixed liquid and the water phase mixed liquid are uniformly mixed, nitrogen is passed through the mixed liquid for deoxygenation under stirring conditions, and the mixture is heated to 50°C. Azobisisobutyramidine hydrochloride is added dropwise at a concentration of 0.025 wt.% based on the total weight of acrylamide, sodium methacryloyloxyethyl dimethyl ammonium chloride and bis(dodecylamide)ethylene, and the reaction is continued at the temperature for 4 hours to obtain a modified bio-glue fracturing fluid thickener.

[0039] Example 3

[0040] A modified bio-gel fracturing fluid thickener is prepared by the following preparation method:

[0041] S1, 16 parts by weight of acrylamide, 14 parts by weight of methacryloyloxyethyl dimethyl benzenesulfonate sodium ammonium chloride, 6 parts by weight of bis(dodecylamide)ethylene and 60 parts by weight of water were mixed and stirred to obtain an aqueous phase mixture;

[0042] S2, 7 parts by weight of an emulsifier and 35 parts by weight of white oil were mixed uniformly to obtain an oil phase mixture; wherein the emulsifier was a mixture of span-60 and tween-60, and the weight ratio of the two was 1:0.3;

[0043] S3. The oil phase mixed liquid and the water phase mixed liquid are uniformly mixed, nitrogen is passed through the mixed liquid for deoxygenation under stirring conditions, and the mixture is heated to 55°C. Azobisisobutyramidine hydrochloride is added dropwise at a concentration of 0.02 wt.% based on the total weight of acrylamide, sodium methacryloyloxyethyl dimethyl ammonium chloride and bis(dodecylamide)ethylene, and the reaction is continued at the temperature for 2 hours to obtain a modified bio-glue fracturing fluid thickener.

[0044] Example 4

[0045] A modified bio-gel fracturing fluid thickener is prepared by the following preparation method:

[0046] S1, 20 parts by weight of acrylamide, 12 parts by weight of methacryloyloxyethyl dimethyl benzenesulfonate sodium ammonium chloride, 8 parts by weight of bis(dodecylamide)ethylene and 60 parts by weight of water were mixed and stirred to obtain an aqueous phase mixture;

[0047] S2, 6 parts by weight of an emulsifier and 40 parts by weight of white oil are mixed uniformly to obtain an oil phase mixture; wherein the emulsifier is a mixture of span-60 and tween-60, and the weight ratio of the two is 1:0.5;

[0048] S3. The oil phase mixed liquid and the water phase mixed liquid are uniformly mixed, nitrogen is passed through the mixed liquid for deoxygenation under stirring conditions, and the mixture is heated to 60°C. Azobisisobutyramidine hydrochloride is added dropwise at a concentration of 0.03 wt.% of the total weight of acrylamide, sodium methacryloyloxyethyl dimethylbenzenesulfonate ammonium chloride and bis(dodecylamide)ethylene, and the reaction is continued at the temperature for 3 hours to obtain a modified bio-glue fracturing fluid thickener.

[0049] Example 5

[0050] A modified bio-gel fracturing fluid thickener is prepared by the following preparation method:

[0051] S1, 18 parts by weight of acrylamide, 11 parts by weight of methacryloyloxyethyl dimethyl benzenesulfonate sodium ammonium chloride, 6 parts by weight of bis(dodecylamide)ethylene and 60 parts by weight of water were mixed and stirred to obtain an aqueous phase mixture;

[0052] S2, 8 parts by weight of an emulsifier and 45 parts by weight of white oil are mixed uniformly to obtain an oil phase mixture; wherein the emulsifier is a mixture of span-60 and tween-60, and the weight ratio of the two is 1:0.4;

[0053] S3. The oil phase mixed liquid and the water phase mixed liquid are uniformly mixed, nitrogen is passed through the mixed liquid for deoxygenation under stirring conditions, and the mixture is heated to 65°C. Azobisisobutyramidine hydrochloride is added dropwise at a concentration of 0.035 wt.% based on the total weight of acrylamide, sodium methacryloyloxyethyl dimethyl ammonium chloride and bis(dodecylamide)ethylene, and the reaction is continued at the temperature for 4 hours to obtain a modified bio-glue fracturing fluid thickener.

[0054] Performance Testing:

[0055] (1) Variable viscosity performance

[0056] The biogel fracturing fluid thickeners prepared in Examples 1-5 were added to water at a ratio of 0.1wt.% to 0.55wt.% under stirring at 2000 r / min to prepare biogel fracturing fluids, and the apparent viscosity was tested. The specific test results are shown in Table 1 below.

[0057] Table 1: Viscosity changes of the fracturing fluid prepared in the examples with the addition amount

[0058] Table 1 shows the change of viscosity with the amount added after Examples 1-5 are prepared into fracturing fluids. It can be seen from Table 1 that after the biogel fracturing fluid thickener prepared in Examples 1-5 is prepared into fracturing fluids, the viscosity of the fracturing fluid increases with the increase of the thickener ratio. When the amount added is 0.1wt.%, the viscosity is maintained at 8-12mPa.s. When the amount added is gradually increased, the viscosity of the fracturing fluid also increases. When the amount added is increased to 0.55wt.%, the viscosity of the fracturing fluid increases to 97-101mPa.s, indicating that the prepared thickener has a good viscosity changing function.

[0059] (2) Low viscosity drag reduction and viscosity

[0060] The biogel fracturing fluid thickeners prepared in Examples 1-5 were added to water under stirring at 2000 r / min to prepare 0.05 wt.% biogel low-viscosity fracturing fluids, and the viscosity and drag reduction performance were tested. The specific test results are shown in Table 2 below.

[0061] Table 2: Viscosity and drag reduction rate of the examples after being formulated into low-viscosity slippery water.

[0062] Table 2 shows the viscosity and drag reduction rate of Examples 1-5 after being prepared into low-viscosity slick water fracturing fluid at 0.05wt.%. It can be seen from Table 2 that the viscosity of the fracturing fluid is less than 5mPa.s, maintained between 2.8-4.1mPa.s, and the drag reduction rate is greater than 75%, with the highest reaching 78.8%.

[0063] (3) Heat and shear resistance

[0064] According to the standard "SY / T 5107 Water-based Fracturing Fluid Performance Evaluation Method", the 0.4wt.% biogel fracturing fluid prepared in Examples 1-5 was tested at 100s. -1 , and the viscosity after shearing for 120 minutes at 150°C to verify its heat resistance and shear resistance. The specific test results are shown in Table 3 below.

[0065] Table 3: Heat and shear resistance performance of the examples

[0066] From the test results in Table 3, it can be seen that the viscosity of the biogel fracturing fluid prepared in Examples 1-5 is maintained above 50 mPa.s after the temperature shear test, which meets the standard requirements, proving that the modified biogel fracturing fluid has good temperature and shear resistance.

[0067] (4) Sand carrying performance

[0068] Example 3 was prepared into a 0.4wt.% bio-gel fracturing fluid, and its sand-carrying capacity was tested. 20 / 40 mesh ceramsite with a sand-to-liquid ratio of 36% was added to the fracturing fluid, stirred evenly, and its static sand-suspending capacity was tested. The specific test results are shown in FIG. Figure 2 As shown in the figure, it can be seen that after the sand was suspended for two hours, there was no obvious sedimentation, indicating that the fracturing fluid has a good sand carrying capacity.

[0069] (4) Performance after gel breaking

[0070] Referring to the standard "SY / T 5107 Water-Based Fracturing Fluid Performance Evaluation Method", the surface, interfacial tension, anti-swelling performance, residue and core damage rate of the 0.4wt.% biogel fracturing fluid prepared in Examples 1 to 5 were tested at 95°C for 120 minutes. The specific test results are shown in Table 4 below.

[0071] Table 4: Performance data of the fracturing fluid prepared in the embodiment after gel breaking

[0072] As shown in Table 4, the viscosity of the biogel fracturing fluid prepared in Examples 1-5 after gel breaking is 2.3-3.2 mPa.s; the surface tension is in the range of 22.1 N / m-22.9 mN / m, and the interfacial tension is in the range of 0.81 N / m-0.96 mN / m, which has lower surface and interfacial tensions, and is helpful for post-fracturing flowback; the anti-swelling rate is maintained at more than 80%, which can prevent clay from swelling and migration; in addition, the core damage rate of the fracturing fluid gel breaking fluid is maintained below 10%, and the residue content is maintained below 5 mg / L, which can indeed achieve truly low damage.

[0073] The thickener of Example 3 and the polyacrylamide thickener of the comparative example were used to prepare low-viscosity slippery water at a ratio of 0.05wt.% and high-viscosity sand-carrying liquid at a ratio of 0.4wt.%, respectively, and their performances were tested respectively. The results are shown in Table 5.

[0074] From Table 5, Figure 3 and Figure 4 It can be seen that compared with the comparative example, the thickener prepared in the embodiment provided by the present invention is superior in various functions such as viscosity change, anti-swelling, resistance reduction, temperature resistance and shear resistance, with lower residue, less damage and better temperature resistance and shear resistance.

[0075] Table 5 Comparative performance table

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A modified bio-gel fracturing fluid thickener, characterized in that: The modified bio-gel fracturing fluid thickener is prepared by polymerizing a water phase mixed liquid and an oil phase mixed liquid; The components of the aqueous phase mixed liquid include: by weight, 10-20 parts of acrylamide, 10-15 parts of sodium methacryloyloxyethyl dimethyl benzenesulfonate ammonium chloride, 5-8 parts of bis(dodecylamide)ethylene and 60 parts of water; The components of the oil phase mixed liquid include: by weight, 4-8 parts of emulsifier and 35-45 parts of white oil.

2. The modified bio-gel fracturing fluid thickener according to claim 1, characterized in that: The emulsifier is a mixture of span-60 and tween-60.

3. The modified bio-gel fracturing fluid thickener according to claim 2, characterized in that: The weight ratio of span-60 to tween-60 is 1:(0.3-0.5).

4. A method for preparing a modified bio-gel fracturing fluid thickener according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, mixing acrylamide, sodium methacryloyloxyethyl dimethyl benzenesulfonate ammonium chloride, bis(dodecylamide)ethylene and water to obtain an aqueous phase mixture; S2, mixing the emulsifier and the white oil evenly to obtain an oil phase mixed liquid; S3, uniformly mixing the oil phase mixed liquid and the water phase mixed liquid, and heating; dropping azobisisobutylamidine hydrochloride into the reaction mixed liquid, and continuing the reaction to obtain a modified bio-gel fracturing fluid thickener.

5. The preparation method according to claim 4, characterized in that: In step S3, the oil phase mixed liquid and the water phase mixed liquid are uniformly mixed, nitrogen is passed through the mixed liquid to deoxygenate the mixed liquid under stirring, and the mixed liquid is heated.

6. The preparation method according to claim 5, characterized in that: In step S3, the oil phase mixed liquid and the water phase mixed liquid are uniformly mixed, nitrogen is passed through the mixed liquid to deoxygenate the mixed liquid under stirring conditions, and the mixed liquid is heated to 45° C.-65° C.

7. The preparation method according to claim 4, characterized in that: In step S3, 0.02 wt. % to 0.035 wt. % of azobisisobutyramidine hydrochloride based on the total weight of acrylamide, sodium methacryloyloxyethyl dimethylbenzenesulfonate ammonium chloride and bis(dodecylamide)ethylene is added dropwise to the reaction mixture.

8. The preparation method according to claim 4, characterized in that: In step S3, azobisisobutylamidine hydrochloride is added dropwise to the reaction mixture, and the reaction is continued at a temperature of 100 °C.

9. The preparation method according to claim 8, characterized in that: In step S3, azobisisobutylamidine hydrochloride is added dropwise to the reaction mixture, and the reaction is continued by keeping the temperature for 2 h to 4 h.

10. Use of the modified biogel fracturing fluid thickener according to any one of claims 1 to 3 in hydraulic fracturing modification.

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