Low-concentration high-temperature-resistant guanidine gum fracturing fluid system and preparation method thereof

Abstract

The invention relates to the technical field of oilfield chemistry, and provides a low-concentration high-temperature-resistant guanidine gum fracturing fluid system and a preparation method thereof. The invention relates to a low-concentration high-temperature-resistant guanidine gum fracturing fluid system. The guanidine gum fracturing fluid system is prepared from the following raw materials in percentage by weight: 0.2 to 0.4 percent of guanidine gum, 0.05 to 0.1 percent of cross-linking agent, 0.03 to 0.05 percent of gel breaker, 0.01 to 0.03 percent of bactericide and 0.05 to 0.1 percent of temperature stabilizer, and the balance of water. The cross-linking agent is a nano cross-linking agent, and the nano cross-linking agent is prepared from the following raw materials in parts by weight: 20 to 25 parts of borate, 1 to 1.5 parts of nano metal oxide particles, 65 to 75 parts of phenyl triazine alcohol compound, 30 to 50 parts of water and 1 to 3 parts of catalyst. According to the technical scheme, the problem of poor high-temperature resistance of a guanidine gum fracturing fluid system in the prior art is solved.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, and in particular to a low-concentration high-temperature resistant guar gum fracturing fluid system and a preparation method thereof. Background Art

[0002] Guar gum is a natural high molecular polymer extracted from guar beans, which can swell in water to form a high viscosity solution. Guar gum fracturing fluid system is a fracturing fluid system with guar gum and its derivatives as the main components. It is widely used in oil production due to its good thickening, sand carrying and compatibility properties. However, the guar gum fracturing fluid system still has shortcomings in terms of high temperature resistance. Under high temperature environment, the guar gum fracturing fluid system is prone to thermal degradation, cross-linking agent failure and other problems, which reduce the viscosity of the fracturing fluid and weaken the sand carrying capacity, thereby affecting the conductivity of the fracture, reducing the fracturing production increase effect, and bringing difficulties to subsequent oil and gas production, well repair and other operations, increasing operational risks and costs. Therefore, it is very necessary to develop a guar gum fracturing fluid system with high temperature resistance. Summary of the invention

[0003] The invention provides a low-concentration high-temperature resistant guar gum fracturing fluid system and a preparation method thereof, which solves the problem of poor high-temperature resistance of the guar gum fracturing fluid system in the related art.

[0004] The technical scheme of the present invention is as follows: The present invention proposes a low-concentration high-temperature resistant guar gum fracturing fluid system, wherein the raw materials of the guar gum fracturing fluid system are composed of the following components in weight percentage: guar gum 0.2% to 0.4%, cross-linking agent 0.05% to 0.1%, gel breaker 0.03% to 0.05%, bactericide 0.01% to 0.03%, temperature stabilizer 0.05% to 0.1%; the balance is water; The cross-linking agent comprises the following raw materials by weight: 20-25 parts of borate, 1-1.5 parts of nano metal oxide particles, 65-75 parts of phenyl triazine alcohol compound, 30-50 parts of water, and 1-3 parts of catalyst.

[0005] As a further technical solution, the phenyltriazine alcohol compound includes one or two of 6-anilino-1,3,5-triazine-2,4-dithiol and 5-[(2-ethylphenyl)amino]-6-methyl-1,2,4-triazine-3-ol.

[0006] As a further technical solution, the borate includes one or more of sodium borate, zinc borate, and iron borate.

[0007] As a further technical solution, the catalyst includes one or both of sodium hydroxide and potassium hydroxide.

[0008] As a further technical solution, the nano metal oxide particles include one or more of nano titanium dioxide, nano zirconium oxide, and nano chromium trioxide.

[0009] As a further technical solution, when the nano metal oxide particles are composed of nano titanium dioxide, nano zirconium oxide, and nano chromium trioxide, the mass ratio of the nano titanium dioxide, nano zirconium oxide, and nano chromium trioxide is 6:4:2-3.

[0010] In the present invention, nano titanium dioxide, nano zirconium oxide and nano chromium trioxide are added simultaneously as nano metal oxide particles, and the synergistic effect of the three is exerted to effectively inhibit the thermal motion and degradation of the guar gum molecular chain, reduce the negative impact of high temperature on the viscosity and rheological properties of the fracturing fluid, and further improve the high temperature resistance of the guar gum fracturing fluid system.

[0011] As a further technical solution, the nano metal oxide particles are modified nano metal oxide particles, and the modified nano metal oxide particles are nano metal oxide particles modified by a modifier, and the modifier is 5-cyano-4-dimethyl-3-phenyl-2-thiophenecarboxamide.

[0012] In the present invention, 5-cyano-4-dimethyl-3-phenyl-2-thiophenecarboxylic acid amine is used as a modifier to modify the nano metal oxide particles, thereby enhancing the dispersibility and thermal stability of the nano metal oxide particles and further improving the high temperature resistance of the guar fracturing fluid system.

[0013] As a further technical solution, the mass ratio of the modifier to the nano metal oxide particles is 1-2:15.

[0014] As a further technical solution, the preparation method of the modified nano metal oxide particles comprises the following steps: dispersing the modifier in a solvent, adding the nano metal oxide particles, stirring, filtering and drying to obtain the modified nano metal oxide particles.

[0015] As a further technical solution, the solvent is acetone, and the mass ratio of the solvent to the nano metal oxide particles is 10:1.

[0016] As a further technical solution, the stirring speed is 300 r / min and the stirring time is 2 h.

[0017] As a further technical solution, the breaker includes one or more of ammonium persulfate, sodium persulfate, and potassium persulfate.

[0018] As a further technical solution, the bactericide includes one or both of glutaraldehyde and dithiocyanomethane.

[0019] As a further technical solution, the temperature stabilizer is temperature stabilizer BA1-26.

[0020] The present invention also provides a method for preparing a low-concentration high-temperature resistant guar gum fracturing fluid system, comprising the following steps: S1, mixing the borate, nano-metal oxide particles, phenyl triazine alcohol compound and water in the cross-linking agent raw material uniformly to obtain a mixture, adding a catalyst to the mixture, and stirring to obtain a cross-linking agent; S2, mixing guar gum, bactericide, temperature stabilizer and water in the guar gum fracturing fluid system to obtain a base fluid; S3: adding a cross-linking agent and a gel breaker to the base fluid, stirring until a gel is formed, and obtaining the guar gum fracturing fluid system.

[0021] As a further technical solution, in S3, the pH of the base liquid is adjusted to 10 before adding the cross-linking agent.

[0022] As a further technical solution, the mixing temperature in S1 is 70-90° C., and the stirring time is 1-2 h.

[0023] The working principle and beneficial effects of the present invention are: In the present invention, guar gum is used as a thickener, and a nano cross-linking agent and a gel breaker are added to prepare a guar gum fracturing fluid system. The phenyl triazine alcohol compound in the nano cross-linking agent can form a stable and efficient cross-linked network structure, the interaction between the molecular chains is increased, and the movement of the molecular chains is restricted in a high temperature environment, thereby improving the high temperature resistance of the guar gum fracturing fluid system. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In the following examples and comparative examples: Guar gum: Hydroxypropyl guar gum, galactomannan content is 80wt%, the manufacturer is Shaanxi Senrui Petroleum Technology Development Co., Ltd.; Nano titanium dioxide: average particle size is 50nm, rutile type; Nano-zirconia: average particle size is 50nm, monoclinic phase; Nano chromium trioxide: average particle size is 50nm.

[0026] Example 1 A low-concentration, high-temperature resistant guar gum fracturing fluid system, wherein the raw materials of the guar gum fracturing fluid system are composed of the following components in weight percentage: 0.2% guar gum, 0.05% cross-linking agent, 0.03% ammonium persulfate, 0.01% glutaraldehyde, 0.05% temperature stabilizer BA1-26, and the balance is water; A method for preparing a low-concentration high-temperature resistant guar gum fracturing fluid system comprises the following steps: S1, weighing 20 parts of sodium borate, 1 part of nano metal oxide particles, 65 parts of 6-anilino-1,3,5-triazine-2,4-dithiol, and 30 parts of water, mixing them evenly, heating them to 60° C., adding 1 part of sodium hydroxide, and stirring for 2 hours to obtain a crosslinking agent, wherein the nano metal oxide particles are nano titanium dioxide; S2. Weigh and prepare the materials according to the mass percentage of each substance in the raw material of the guar gum fracturing fluid system; S3, mixing guar gum, glutaraldehyde, temperature stabilizer BA1-26 and water to obtain a base liquid; S4. Adjust the pH of the base fluid to 10, add a cross-linking agent and ammonium persulfate into the base fluid, and stir until a gel is formed to obtain a guar gel fracturing fluid system.

[0027] Example 2 A low-concentration high-temperature resistant guar gum fracturing fluid system, comprising the following components in weight percentage: guar gum 0.4%, cross-linking agent 0.1%, sodium persulfate 0.05%, glutaraldehyde 0.03%, temperature stabilizer BA1-26 0.1%, and the balance water; A method for preparing a low-concentration high-temperature resistant guar gum fracturing fluid system comprises the following steps: S1, weighing 25 parts of iron borate, 1.5 parts of nano metal oxide particles, 75 parts of 6-anilino-1,3,5-triazine-2,4-dithiol, and 50 parts of water, mixing them evenly, heating them to 80° C., adding 3 parts of potassium hydroxide, and stirring for 1 hour to obtain a cross-linking agent, wherein the nano metal oxide particles are nano chromium trioxide; S2. Weigh and prepare the materials according to the mass percentage of each substance in the raw material of the guar gum fracturing fluid system; S3, mixing guar gum, dithiocyanomethane, temperature stabilizer BA1-26 and water to obtain a base liquid; S4. Adjust the pH of the base fluid to 10, add a cross-linking agent and potassium persulfate in percentage by weight to the base fluid, and stir until a gel is formed to obtain a guar gel fracturing fluid system.

[0028] Example 3 A low-concentration high-temperature resistant guar gum fracturing fluid system, comprising the following components in weight percentage: guar gum 0.4%, cross-linking agent 0.1%, potassium persulfate 0.05%, glutaraldehyde 0.03%, temperature stabilizer BA1-26 0.1%, and the balance water; A method for preparing a low-concentration high-temperature resistant guar gum fracturing fluid system comprises the following steps: S1. Weigh 25 parts of iron borate, 1.5 parts of nano metal oxide particles, 75 parts of 5-[(2-ethylphenyl)amino]-6-methyl-1,2,4-triazine-3-ol, and 50 parts of water, mix them evenly, heat them to 80° C., add 3 parts of potassium hydroxide, and stir for 1 hour to obtain a cross-linking agent, wherein the nano metal oxide particles are nano chromium trioxide; S2. Weigh and prepare the materials according to the mass percentage of each substance in the raw material of the guar gum fracturing fluid system; S3, mixing guar gum, dithiocyanomethane, temperature stabilizer BA1-26 and water to obtain a base liquid; S4. Adjust the pH of the base fluid to 10, add a cross-linking agent and potassium persulfate in percentage by weight to the base fluid, and stir until a gel is formed to obtain a guar gel fracturing fluid system.

[0029] Example 4 Compared with Example 3, the difference of Example 4 is that the nano-titanium dioxide is replaced by nano-titanium dioxide and nano-zirconia in a mass ratio of 6:2.

[0030] Example 5 Compared with Example 3, the difference of Example 5 is that the nano titanium dioxide is replaced by nano titanium dioxide and nano chromium trioxide in a mass ratio of 6:2.

[0031] Example 6 Compared with Example 4, the difference of Example 6 is that the nano metal oxide particles are composed of nano titanium dioxide, nano zirconium oxide, and nano chromium trioxide in a mass ratio of 6:4:2.

[0032] Example 7 Compared with Example 4, the difference of Example 7 is that the nano metal oxide particles are composed of nano titanium dioxide, nano zirconium oxide and nano chromium trioxide in a mass ratio of 6:4:3.

[0033] Example 8 The preparation method of modified nano metal oxide particles comprises the following steps: dispersing 1 part of 5-cyano-4-dimethyl-3-phenyl-2-thiophenecarboxylic acid amine in 150 parts of acetone, adding 15 parts of nano metal oxide particles, stirring at 300 r / min for 2 hours, filtering and drying to obtain modified nano metal oxide particles, wherein the nano metal oxide particles are composed of nano titanium dioxide, nano zirconium oxide and nano chromium trioxide in a mass ratio of 6:4:3; Compared with Example 7, the difference of Example 8 is that the nano metal oxide particles are replaced with an equal amount of modified nano metal oxide particles obtained by the above preparation method.

[0034] Example 9 Compared with Example 8, the difference in Example 9 is that the added amount of 5-cyano-4-dimethyl-3-phenyl-2-thiophenecarboxamide is 2 parts.

[0035] Comparative Example 1 Compared with Example 3, the difference in Comparative Example 1 is that 6-anilino-1,3,5-triazine-2,4-dithiol is replaced by an equal amount of ethylenediaminetetraacetic acid.

[0036] Comparative Example 2 Compared with Example 3, Comparative Example 2 is different in that 6-anilino-1,3,5-triazine-2,4-dithiol is replaced by an equal amount of ethanolamine.

[0037] The guar gum fracturing fluid systems prepared in Examples 1 to 9 and Comparative Examples 1 to 2 were tested according to the following method: 1. Viscosity: Test the viscosity of the sample according to the test method specified in SY / T 5107-2016 "Performance Evaluation Method of Water-Based Fracturing Fluid".

[0038] The test results are shown in the following table: Table 1 Performance test results of guar gum fracturing fluid systems prepared in Examples 1 to 9 and Comparative Examples 1 to 2

[0039] Compared with Comparative Examples 1 and 2, Example 3 adds a phenyl triazone compound. As a result, the viscosity of the fracturing fluid of Example 3 after shearing at 120°C for 60 minutes and the viscosity after shearing at 160°C for 60 minutes are both greater than those of Comparative Examples 1 and 2, indicating that when a phenyl triazone compound is added, the high temperature resistance of the guar gum fracturing fluid system can be improved.

[0040] In Examples 2 and 3, different types of phenyl triazine alcohol compounds were added. As a result, the viscosity of the fracturing fluid of Example 3 after shearing at 120°C for 60 minutes and the viscosity after shearing at 160°C for 60 minutes were both greater than those of Example 2, indicating that when the added phenyl triazine alcohol compound was 5-[(2-ethylphenyl)amino]-6-methyl-1,2,4-triazine-3-ol, the obtained guar gum fracturing fluid system had better high temperature resistance.

[0041] Compared with Examples 4 and 5, Examples 6 and 7 simultaneously add nano titanium dioxide, nano chromium oxide, and nano chromium trioxide as nano metal oxide particles. As a result, the viscosity of the fracturing fluid of Examples 6 and 7 after shearing at 120°C for 60 minutes and the viscosity after shearing at 160°C for 60 minutes are both greater than those of Examples 4 and 5, indicating that nano titanium dioxide, nano chromium oxide, and nano chromium trioxide play a synergistic role and can further improve the high temperature resistance of the guar gum fracturing fluid system.

[0042] Compared with Example 7, Examples 8 and 9 added modified nano-metal oxide particles. As a result, the viscosity of the fracturing fluids of Examples 8 and 9 after shearing at 120°C for 60 minutes and after shearing at 160°C for 60 minutes were both greater than those of Example 7, indicating that when modified nano-metal oxide particles were added, the high temperature resistance of the obtained guar gum fracturing fluid system was better.

[0043] The above are only 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 in the protection scope of the present invention.

Claims

1. A low-concentration high-temperature resistant guar gum fracturing fluid system, characterized in that: The raw materials of the guar gum fracturing fluid system are composed of the following components in weight percentage: guar gum 0.2% to 0.4%, cross-linking agent 0.05% to 0.1%, breaker 0.03% to 0.05%, bactericide 0.01% to 0.03%, temperature stabilizer 0.05% to 0.1%; the balance is water; The cross-linking agent comprises the following raw materials in parts by weight: 20-25 parts of borate, 1-1.5 parts of nano metal oxide particles, 65-75 parts of phenyl triazine alcohol compound, 30-50 parts of water, and 1-3 parts of catalyst.

2. A low-concentration high-temperature resistant guar gum fracturing fluid system according to claim 1, characterized in that: The phenyltriazine alcohol compound includes one or two of 6-anilino-1,3,5-triazine-2,4-dithiol and 5-[(2-ethylphenyl)amino]-6-methyl-1,2,4-triazine-3-ol.

3. A low-concentration high-temperature resistant guar gum fracturing fluid system according to claim 1, characterized in that: Also includes at least one of the following technical features: The borate includes one or more of sodium borate, zinc borate, and iron borate; The catalyst includes one or both of sodium hydroxide and potassium hydroxide.

4. A low-concentration high-temperature resistant guar gum fracturing fluid system according to claim 1, characterized in that: The nano metal oxide particles include one or more of nano titanium dioxide, nano zirconium oxide, and nano chromium trioxide.

5. A low-concentration high-temperature resistant guar gum fracturing fluid system according to claim 4, characterized in that: When the nano metal oxide particles are composed of nano titanium dioxide, nano zirconium oxide and nano chromium trioxide, the mass ratio of the nano titanium dioxide, nano zirconium oxide and nano chromium trioxide is 6:4:2-3.

6. A low-concentration high-temperature resistant guar gum fracturing fluid system according to claim 4, characterized in that: The nano metal oxide particles are modified nano metal oxide particles, which are obtained by modifying nano metal oxide particles with a modifier, and the modifier is 5-cyano-4-dimethyl-3-phenyl-2-thiophenecarboxyamine.

7. A low-concentration high-temperature resistant guar gum fracturing fluid system according to claim 6, characterized in that: The mass ratio of the modifier to the nano metal oxide particles is 1-2:

15.

8. A low-concentration high-temperature resistant guar gum fracturing fluid system according to claim 1, characterized in that: The degumming agent includes one or more of ammonium persulfate, sodium persulfate, and potassium persulfate.

9. A low-concentration high-temperature resistant guar gum fracturing fluid system according to claim 1, characterized in that: Also includes at least one of the following technical features: The bactericide comprises one or two of glutaraldehyde and dithiocyanomethane; The temperature stabilizer is temperature stabilizer BA1-26.

10. The method for preparing a low-concentration high-temperature resistant guar gum fracturing fluid system according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1, mixing the borate, nano-metal oxide particles, phenyl triazine alcohol compound and water in the cross-linking agent raw materials uniformly, adding a catalyst, and stirring to obtain a cross-linking agent; S2, mixing guar gum, bactericide, temperature stabilizer and water in the guar gum fracturing fluid system to obtain a base fluid; S3, adding a cross-linking agent and a breaker to the base fluid, stirring until a gel is formed, and obtaining the guar gum fracturing fluid system.

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