Salt-resistant emulsion type fracturing fluid thickening agent and preparation method thereof

Abstract

The invention relates to the technical field of thickening agents, in particular to a salt-resistant emulsion type fracturing fluid thickening agent and a preparation method thereof. The salt-resistant emulsion type fracturing fluid thickening agent comprises deionized water, a polymeric monomer, an oil solvent, an emulsifier, an initiator and a phase inversion agent, a preparation method of the salt-resistant emulsion type fracturing fluid thickening agent is simple and low in cost, all adopted raw materials are industrially pure, the preparation cost is reduced, meanwhile, the preparation method is simple and safe, and the salt-resistant emulsion type fracturing fluid thickening agent is suitable for industrial production. The prepared emulsion type fracturing fluid thickening agent is good in stability, not prone to layering, good in water solubility, convenient to apply to site construction, good in temperature resistance and salt resistance, high in batch uniformity of the obtained emulsion type fracturing fluid thickening agent product and convenient to popularize and use in a large range.

Description

Technical Field

[0001] The invention relates to the technical field of thickeners, and in particular to a salt-resistant emulsion-type fracturing fluid thickener and a preparation method thereof. Background Art

[0002] The process of hydraulic fracturing of oil layers is to use a high-pressure and large-displacement pump on the ground, and utilize the principle of liquid pressure transmission to inject a liquid with a certain viscosity (usually called fracturing fluid) into the oil layer at a pressure greater than the absorption capacity of the oil layer, and gradually increase the pressure in the wellbore, thereby creating high pressure at the bottom of the well. When this pressure is greater than the ground stress near the well wall and the tensile strength of the formation rock, cracks will be generated in the formation near the bottom of the well: continue to inject sand-carrying fluid with proppants, the cracks extend forward and are filled with proppants. After the well is shut down, the cracks are closed on the proppants, thereby forming sand-filled cracks with certain geometric dimensions and high conductivity in the formation near the bottom of the well, so as to achieve the purpose of increasing production and injection of the well. Commonly used proppants include quartz sand, expanded clay, etc.

[0003] Fracturing fluid is the working fluid used in fracturing construction. It has good compatibility with formation cores and fluids. Fracturing fluid can be classified according to its chemical properties into water-based fracturing fluid, oil-based fracturing fluid, emulsion fracturing fluid, foam fracturing fluid, alcohol-based fracturing fluid and gas fracturing fluid. Among them, emulsion fracturing fluid is suitable for water-sensitive and low-pressure formations.

[0004] Traditional polymer thickeners for fracturing fluids are mainly in powder form. Since powder polymers dissolve slowly when used, even instant products require a certain amount of time to dissolve. When preparing the fluid, it not only increases the workload, but also causes shear degradation of the product, which is not only inconvenient to use, but also affects the product's use effect. Based on this, the use of inverse emulsion polymerization to synthesize drilling fluid treatment agents has gradually gained attention. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a salt-resistant emulsion fracturing fluid thickener in view of the deficiencies of the above-mentioned prior art, comprising deionized water, a polymerized monomer, an oil solvent, an emulsifier, an initiator and a phase transfer agent. The preparation method is simple and the cost is low. The prepared emulsion fracturing fluid thickener has good stability, is not easy to stratify, has good water solubility, is easy to be applied to on-site construction, has good temperature resistance and salt resistance, and the obtained emulsion fracturing fluid thickener product has high batch uniformity, which is convenient for large-scale promotion and use.

[0006] The invention provides a salt-resistant emulsion fracturing fluid thickener, which is composed of the following raw materials in parts by weight: 92 to 110 parts of deionized water, 38 to 52 parts of polymerization monomers, 86 to 100 parts of oil solvents, 8 to 11 parts of emulsifiers, 0.5 to 0.7 parts of initiators and 0.2 to 0.3 parts of phase transition agents.

[0007] The salt-resistant emulsion fracturing fluid thickener provided by the present invention is composed of the following raw materials in parts by weight: 100 parts of deionized water, 40 parts of polymerization monomers, 90 parts of oil solvents, 9 parts of emulsifiers, 0.5 parts of initiators and 0.2 parts of phase transition agents.

[0008] The present invention also provides a method for preparing the above-mentioned salt-resistant emulsion fracturing fluid thickener, comprising the following steps:

[0009] S1, adding the polymerization monomer mixture to deionized water, stirring thoroughly, and then adding sodium hydroxide solution to adjust the pH value to 7-8 to obtain an aqueous phase mixed solution;

[0010] S2, adding an emulsifier to the oil solvent and stirring thoroughly for 20 minutes to obtain an oil phase mixture;

[0011] S3, mixing the aqueous phase mixture prepared in S1 and the oil phase mixture prepared in S2, introducing nitrogen to deoxygenate for 30 minutes, adding an initiator, and fully stirring for 60 minutes at a high speed of 3000 rpm / min and a temperature of 30° C. to perform a polymerization reaction to obtain a preliminary emulsion;

[0012] S4. Add a phase inversion agent to the preliminary emulsion prepared in S3 to obtain a salt-resistant emulsion-type fracturing fluid thickener.

[0013] According to the preparation method provided by the present invention, the polymerizable monomer in S1 is a mixture of acrylamide, N-vinyl pyrrolidone and 2-acrylamido-2-methylpropanesulfonic acid or sodium acrylsulfonate.

[0014] According to the preparation method provided by the present invention, the oil solvent in S2 is a mixture of white oil and liquid paraffin.

[0015] According to the preparation method provided by the present invention, the emulsifier in S2 is one of Span 80, Span 85, Tween 60 or Tween 80.

[0016] According to the preparation method provided by the present invention, the initiator in S3 is one of potassium sulfate, sodium sulfite, ammonium persulfate, sodium bisulfite or potassium persulfate.

[0017] According to the preparation method provided by the present invention, the phase transition agent in S4 is NP-10 or NP-40.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] The invention provides a salt-resistant emulsion fracturing fluid thickener, comprising deionized water, a polymerized monomer, an oil solvent, an emulsifier, an initiator and a phase transfer agent. The preparation method is simple and low in cost. The raw materials used in the preparation method are all industrially pure, and the preparation method is simple and safe while reducing the preparation cost. The prepared emulsion fracturing fluid thickener has good stability, is not easy to be separated, has good water solubility, is easy to be applied to on-site construction, has good temperature resistance and salt resistance, and the obtained emulsion fracturing fluid thickener product has high batch uniformity and is easy to be promoted and used on a large scale. DETAILED DESCRIPTION

[0020] Example 1

[0021] This embodiment provides a specific composition of a salt-resistant emulsion-type fracturing fluid thickener, which specifically includes: deionized water, polymerizable monomers, oil solvent, emulsifier, initiator and phase inversion agent;

[0022] The polymerizable monomers are a mixture of acrylamide, N-vinyl pyrrolidone and 2-acrylamido-2-methylpropanesulfonic acid or sodium acrylsulfonate, wherein 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and sodium acrylsulfonate are both salt-resistant monomers;

[0023] The oil solvent is a mixture of white oil and liquid paraffin;

[0024] The emulsifier is one of Span 80, Span 85, Tween 60 or Tween 80;

[0025] The initiator is one of potassium sulfate, sodium sulfite, ammonium persulfate, sodium bisulfite or potassium persulfate;

[0026] The phase inverting agent is one of NP-10 and NP-40.

[0027] Example 2

[0028] This embodiment provides a method for preparing an emulsion-type fracturing fluid thickener from the components described in Example 1:

[0029] S1, adding 40 parts by weight of a polymerizable monomer mixture of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-vinyl pyrrolidone to 100 parts by weight of deionized water, stirring thoroughly, and then adding sodium hydroxide solution to adjust the pH value to 8 to obtain an aqueous phase mixed solution;

[0030] The mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-vinylpyrrolidone is 3:1:2;

[0031] S2, adding 9 parts by weight of emulsifier Span 85 to a mixture of 90 parts by weight of white oil and liquid paraffin, and stirring for 20 minutes to obtain an oil phase mixture;

[0032] S3, mixing the aqueous phase mixture prepared in S1 and the oil phase mixture prepared in S2, introducing nitrogen for 30 minutes for deoxygenation, adding 0.5 parts by weight of initiator ammonium persulfate, and fully stirring for 60 minutes at a high speed of 3000 rpm / min and a temperature of 30° C. to carry out polymerization reaction to obtain a preliminary emulsion;

[0033] S4. Add 0.2 parts by weight of phase inversion agent NP-10 to the preliminary emulsion prepared in S3 to prepare a salt-resistant emulsion-type fracturing fluid thickener.

[0034] The reactants used in this embodiment are all commercially available products. The prepared emulsion fracturing fluid thickener has good salt resistance, good stability, is not easy to stratify, has good water solubility, and is easy to be used in on-site construction; at the same time, after shearing at 200°C for 2h, its viscosity is tested to be above 180mPa·s, and has good temperature resistance.

[0035] The salt-resistant emulsion fracturing fluid thickener prepared in this embodiment is used to prepare a salt-resistant emulsion fracturing fluid thickener solution with a mass fraction of 1%. The apparent viscosity is tested in salt-free, 50 g / L, 100 g / L and 150 g / L NaCl solutions, and the test results are 235 mPa·s, 227 mPa·s, 210 mPa·s and 204 mPa·s, respectively. Therefore, the salt-resistant emulsion fracturing fluid thickener prepared in this embodiment has good salt resistance.

[0036] Example 3

[0037] This embodiment provides a method for preparing an emulsion-type fracturing fluid thickener from the components described in Example 1:

[0038] S1, adding 50 parts by weight of a polymerizable monomer mixture of acrylamide, sodium propylene sulfonate and N-vinyl pyrrolidone to 100 parts by weight of deionized water, stirring thoroughly, and then adding sodium hydroxide solution to adjust the pH value to 7 to obtain an aqueous phase mixed solution;

[0039] The mass ratio of acrylamide, sodium propylene sulfonate and N-vinyl pyrrolidone is 3:1:2;

[0040] S2, adding 10 parts by weight of emulsifier Span 80 to a mixture of 100 parts by weight of white oil and liquid paraffin, stirring thoroughly for 23 minutes to obtain an oil phase mixture;

[0041] S3, mixing the aqueous phase mixture prepared in S1 and the oil phase mixture prepared in S2, introducing nitrogen for 30 minutes for deoxygenation, adding 0.5 parts by weight of initiator potassium sulfate, and fully stirring for 60 minutes at a high speed of 3000 rpm / min and a temperature of 30° C. to carry out polymerization reaction to obtain a preliminary emulsion;

[0042] S4. Add 0.2 parts by weight of phase inversion agent NP-40 to the preliminary emulsion prepared in S3 to prepare a salt-resistant emulsion-type fracturing fluid thickener.

[0043] Example 4

[0044] This embodiment provides a method for preparing an emulsion-type fracturing fluid thickener from the components described in Example 1:

[0045] S1, adding 52 parts by weight of a polymerizable monomer mixture of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-vinyl pyrrolidone to 110 parts by weight of deionized water, stirring thoroughly, and then adding sodium hydroxide solution to adjust the pH value to 8 to obtain an aqueous mixed solution;

[0046] The mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-vinylpyrrolidone is 3:1:2;

[0047] S2, adding 11 parts by weight of emulsifier Span 85 to a mixture of 100 parts by weight of white oil and liquid paraffin, and stirring for 18 minutes to obtain an oil phase mixture;

[0048] S3, mixing the aqueous phase mixture prepared in S1 and the oil phase mixture prepared in S2, introducing nitrogen for 30 minutes for deoxygenation, adding 0.7 parts by weight of initiator sodium sulfite, and fully stirring for 60 minutes at a high speed of 3000 rpm / min and a temperature of 30° C. to carry out polymerization reaction to obtain a preliminary emulsion;

[0049] S4. Add 0.3 parts by weight of phase inversion agent NP-10 to the preliminary emulsion prepared in S3 to prepare a salt-resistant emulsion-type fracturing fluid thickener.

[0050] Example 5

[0051] This embodiment provides a method for preparing an emulsion-type fracturing fluid thickener from the components described in Example 1:

[0052] S1, adding 38 parts by weight of a polymerizable monomer mixture of acrylamide, sodium propylene sulfonate and N-vinyl pyrrolidone to 92 parts by weight of deionized water, stirring thoroughly, and then adding sodium hydroxide solution to adjust the pH value to 7.3 to obtain an aqueous mixed solution;

[0053] The mass ratio of acrylamide, sodium propylene sulfonate and N-vinyl pyrrolidone is 3:1:2;

[0054] S2, adding 8 parts by weight of an emulsifier Tween 60 to a mixture of 86 parts by weight of white oil and liquid paraffin, and stirring for 20 minutes to obtain an oil phase mixture;

[0055] S3, mixing the aqueous phase mixture prepared in S1 and the oil phase mixture prepared in S2, introducing nitrogen for 30 minutes for deoxygenation, adding 0.5 parts by weight of initiator potassium persulfate, and fully stirring for 60 minutes at a high speed of 3000 rpm / min and a temperature of 30° C. to carry out polymerization reaction to obtain a preliminary emulsion;

[0056] S4. Add 0.2 parts by weight of phase inversion agent NP-10 to the preliminary emulsion prepared in S3 to prepare a salt-resistant emulsion-type fracturing fluid thickener.

[0057] Example 6

[0058] This embodiment provides a method for preparing an emulsion-type fracturing fluid thickener from the components described in Example 1:

[0059] S1, adding 41 parts by weight of a polymerizable monomer mixture of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-vinyl pyrrolidone to 102 parts by weight of deionized water, stirring thoroughly, and then adding sodium hydroxide solution to adjust the pH value to 7.8 to obtain an aqueous phase mixed solution;

[0060] The mass ratio of acrylamide, 2-acrylamido-2-methylpropanesulfonic acid and N-vinylpyrrolidone is 3:1:2;

[0061] S2, adding 9 parts by weight of an emulsifier Tween 60 to a mixture of 94 parts by weight of white oil and liquid paraffin, and stirring for 20 minutes to obtain an oil phase mixture;

[0062] S3, mixing the aqueous phase mixture prepared in S1 and the oil phase mixture prepared in S2, introducing nitrogen to deoxygenate for 30 minutes, adding 0.6 parts by weight of initiator sodium bisulfite, and fully stirring for 60 minutes at a high speed of 3000 rpm / min and a temperature of 30° C. to carry out polymerization reaction to obtain a preliminary emulsion;

[0063] S4. Add 0.2 parts by weight of phase inversion agent NP-10 to the preliminary emulsion prepared in S3 to prepare a salt-resistant emulsion-type fracturing fluid thickener.

[0064] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the technical essence of the invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A salt-resistant emulsion fracturing fluid thickener, characterized in that: The invention is composed of the following raw materials in parts by weight: 92 to 110 parts of deionized water, 38 to 52 parts of polymerization monomers, 86 to 100 parts of oil solvents, 8 to 11 parts of emulsifiers, 0.5 to 0.7 parts of initiators and 0.2 to 0.3 parts of phase transfer agents.

2. The salt-resistant emulsion fracturing fluid thickener according to claim 1, characterized in that: The invention is composed of the following raw materials in parts by weight: 100 parts of deionized water, 40 parts of polymerization monomers, 90 parts of oil solvents, 9 parts of emulsifiers, 0.5 parts of initiators and 0.2 parts of phase inversion agents.

3. A method for preparing the salt-resistant emulsion fracturing fluid thickener as claimed in claim 1, characterized in that: The following steps are involved: S1, adding the polymerization monomer mixture to deionized water, stirring thoroughly, and then adding sodium hydroxide solution to adjust the pH value to 7-8 to obtain an aqueous phase mixed solution; S2, adding an emulsifier to the oil solvent and stirring thoroughly for 20 minutes to obtain an oil phase mixture; S3, mixing the aqueous phase mixture prepared in S1 and the oil phase mixture prepared in S2, introducing nitrogen for 30 minutes for deoxygenation, adding an initiator, and fully stirring for 60 minutes at a high speed of 3000 rpm / min and a temperature of 30° C. to perform a polymerization reaction to obtain a preliminary emulsion; S4. Add a phase inversion agent to the preliminary emulsion prepared in S3 to obtain a salt-resistant emulsion-type fracturing fluid thickener.

4. The preparation method according to claim 3, characterized in that: The polymerizable monomer in S1 is a mixture of acrylamide, N-vinyl pyrrolidone and 2-acrylamido-2-methylpropanesulfonic acid or sodium acrylsulfonate.

5. The preparation method according to claim 3, characterized in that: The oil solvent in S2 is a mixture of white oil and liquid paraffin.

6. The preparation method according to claim 3, characterized in that: The emulsifier in S2 is one of Span 80, Span 85, Tween 60 or Tween 80.

7. The preparation method according to claim 3, characterized in that: The initiator in S3 is one of potassium sulfate, sodium sulfite, ammonium persulfate, sodium bisulfite or potassium persulfate.

8. The preparation method according to claim 3, characterized in that: The phase inversion agent in S4 is NP-10 or NP-40.