Instant thickening agent suspension for fracturing and preparation method thereof

Abstract

The invention relates to an instant thickening agent suspension for fracturing and a preparation method thereof. According to the technical scheme, the pesticide is prepared from the following components in parts by weight: 350-550 parts of an N, N-dimethylformamide solvent, 30-100 parts of water, 10-30 parts of a suspending agent, 10-50 parts of an inhibitor and 350-500 parts of polymer powder, the preparation method disclosed by the invention has the specific beneficial effects that (1) the preparation method is simple, easy to operate, few in raw material variety, free of heating and polymerization reaction, environment-friendly, pollution-free and low in energy consumption; (2) N, N-dimethylformamide is used for replacing oil substances which are commonly used at present, so that the cost is lower, and the dissolving speed of the thickening agent is higher; n, N-dimethylformamide and water are mutually soluble, and when the thickening agent suspension encounters water, the thickening agent suspension does not need to be subjected to a demulsification process like an oil-based thickening agent suspension. Therefore, the hydration rate is higher than that of the conventional oil-based thickening agent suspension.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum extraction, and in particular to a quick-dissolving thickener suspension for fracturing and a preparation method thereof. Background Art

[0002] Hydraulic fracturing is an effective method to improve oil and gas reservoirs, especially in the exploitation of unconventional energy sources such as shale gas and tight gas, which usually requires continuous mixing and large-volume hydraulic fracturing. Dry powder polyacrylamide needs to be fully dissolved in advance when applied to oil fields. Therefore, the fracturing fluid preparation process is complicated, the equipment required is large, and the construction period is long. It can no longer fully meet the requirements for large-scale oil field fracturing.

[0003] In recent years, inverse emulsion thickeners and suspension-dispersed thickeners have become the main types of fracturing fluid thickeners. These two types of products have fast dissolution speed and can meet the requirements of continuous mixing on site. Due to the poor salt resistance and low effective content (generally around 30%), inverse emulsion thickeners can usually only be used as pre-fluids. Suspension-dispersed thickeners have become the most important thickeners for fracturing fluids due to their high effective content (usually 40%~50%), good temperature and salt resistance, and fast dissolution speed. However, the continuous phase used in suspension-dispersed thickeners is usually oily substances with a high content (40%~60%), and the dissolution process of suspension-dispersed thickeners needs to go through a demulsification stage, which results in high cost and a slightly slow hydration rate for this type of product.

[0004] Therefore, how to provide a thickener with fast hydration rate and low cost has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0005] The purpose of the present invention is to provide a quick-dissolving thickener suspension for fracturing and a preparation method thereof in view of the above-mentioned defects in the prior art. The quick-dissolving thickener suspension has a fast hydration rate and a low production cost. The present invention also takes into account the advantages of high molecular weight, high salt resistance and high temperature resistance of dry powder polyacrylamide, and has a faster dissolution rate and lower cost than conventional oil-based suspensions, thus meeting the technical requirements of large-volume fracturing construction with continuous mixing.

[0006] The instant thickener suspension for fracturing mentioned in the present invention is made of the following components in parts by weight: 350-550 parts of N,N-dimethylformamide solvent, 30-100 parts of water, 10-30 parts of suspending agent, 10-50 parts of inhibitor, and 350-500 parts of polymer powder; the polymer powder is made of polyacrylamide.

[0007] Preferably, the particle size of the polyacrylamide powder is ≤125 μm, and the moisture content of the polyacrylamide powder is ≤10%.

[0008] Preferably, the above-mentioned suspending agent is magnesium aluminum silicate or silicon dioxide, or a mixture of the two.

[0009] Preferably, the silica mentioned above is hydrophilic fumed silica.

[0010] Preferably, the above inhibitor includes any one or more of calcium chloride, calcium chloride dihydrate, magnesium chloride, and magnesium chloride hexahydrate.

[0011] The method for preparing the instant thickener suspension for fracturing mentioned in the present invention comprises the following steps: (1) Add N,N-dimethylformamide solvent and water into the reactor, turn on the stirring motor in the reactor, and set the stirring speed to 60 rpm; (2) Maintain the mixer speed at 60 RPM, turn on the disperser, adjust the speed to 600 RPM, add the suspending agent and inhibitor in sequence, and continue stirring and dispersing for 30 minutes; (3) Keep the speed of the mixer and disperser unchanged, continue to add polyacrylamide powder to the reactor, continue stirring and dispersing for 30 minutes after adding, and obtain a quick-dissolving thickener suspension for fracturing.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The preparation method of the present invention is simple and easy to operate, with a small number of raw materials, no need for heating and polymerization reaction, environmentally friendly, pollution-free, low energy consumption, and in line with the development direction of green and environmentally friendly chemical additives; (2) Using N,N-dimethylformamide instead of the commonly used oil substances is not only cheaper, but also can make the thickener dissolve faster; N,N-dimethylformamide is miscible with water. When the thickener suspension meets water, it does not need to go through the demulsification process like the oil-based thickener suspension. Therefore, its hydration rate is faster than that of conventional oil-based thickener suspension.

[0013] The invention takes into account the advantages of high molecular weight, high salt resistance and high temperature resistance of dry powder polyacrylamide, and has a faster dissolution speed and lower cost than conventional oil-based suspensions, thus meeting the technical requirements of large-volume fracturing construction with continuous mixing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The suspension of Example 1 was added at 1% and heated at 120°C for 170 seconds. -1 Schematic diagram of the heat and shear resistance test under the following conditions; Figure 2 It is a schematic diagram of the hydration rate test of the suspension of Example 2 and the conventional oil-based thickener suspension when the addition amount is 0.3%. DETAILED DESCRIPTION

[0015] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention. Example 1

[0016] The instant polymer suspension emulsion for fracturing mentioned in the present invention comprises the following components in parts by weight: 550 parts of N,N-dimethylformamide, 100 parts of water, 10 parts of anhydrous calcium chloride, 10 parts of magnesium aluminum silicate, and 350 parts of polyacrylamide powder.

[0017] The preparation method of the thickener suspension for fracturing mentioned in the present invention comprises the following steps: (1) Add the measured N,N-dimethylformamide and water into the reactor, turn on the stirring motor in the reactor, and set the stirring speed to 60 PRM; (2) Maintain the mixer speed at 60 RPM, turn on the disperser, adjust the speed to 600 RPM, add the weighed magnesium aluminum silicate and anhydrous calcium chloride in sequence, and continue stirring and dispersing for 30 minutes; (3) Keep the speed of the mixer and disperser unchanged, and continue to add the measured polyacrylamide powder into the reactor. Continue stirring and dispersing for 30 minutes to obtain a quick-dissolving thickener suspension for fracturing. Example 2

[0018] The instant polymer suspension emulsion for fracturing mentioned in the present invention comprises the following components in parts by weight: 350 parts of N,N-dimethylformamide, 40 parts of water, 20 parts of calcium chloride dihydrate, 30 parts of hydrophilic fumed silica, and 400 parts of polyacrylamide powder.

[0019] The preparation process is as follows: The preparation method of the thickener suspension for fracturing of the present invention comprises the following steps: (1) Add the measured N,N-dimethylformamide and water into the reactor, turn on the stirring motor in the reactor, and set the stirring speed to 60 PRM; (2) Maintain the mixer speed at 60 RPM, turn on the disperser, adjust the speed to 600 RPM, add the weighed hydrophilic fumed silica and calcium chloride dihydrate in sequence, and continue stirring and dispersing for 30 minutes; (3) Keep the speed of the mixer and disperser unchanged, and continue to add the measured polyacrylamide powder into the reactor. Continue stirring and dispersing for 30 minutes to obtain a quick-dissolving thickener suspension for fracturing. Example 3

[0020] The instant polymer suspension emulsion for fracturing mentioned in the present invention comprises the following components in parts by weight: 443 parts of N,N-dimethylformamide, 30 parts of water, 20 parts of magnesium chloride hexahydrate, 10 parts of magnesium aluminum silicate, and 500 parts of polyacrylamide powder.

[0021] The preparation process is as follows: The preparation method of the thickener suspension for fracturing of the present invention comprises the following steps: (1) Add the measured N,N-dimethylformamide and water into the reactor, turn on the stirring motor in the reactor, and set the stirring speed to 60 PRM; (2) Maintain the mixer speed at 60 RPM, turn on the disperser, adjust the speed to 600 RPM, add the weighed magnesium aluminum silicate and calcium chloride dihydrate in sequence, and continue stirring and dispersing for 30 minutes; (3) Keep the speed of the mixer and disperser unchanged, and continue to add the measured polyacrylamide powder into the reactor. Continue stirring and dispersing for 30 minutes to obtain a quick-dissolving thickener suspension for fracturing. Example 4

[0022] The instant polymer suspension emulsion for fracturing mentioned in the present invention comprises the following components in parts by weight: 350 parts of N,N-dimethylformamide, 40 parts of water, 50 parts of magnesium chloride, 30 parts of a mixture of magnesium aluminum silicate or silicon dioxide, and 400 parts of polyacrylamide powder, wherein magnesium aluminum silicate or silicon dioxide is mixed in a weight ratio of 1:2; The preparation process is as follows: The preparation method of the thickener suspension for fracturing of the present invention comprises the following steps: (1) Add the measured N,N-dimethylformamide and water into the reactor, turn on the stirring motor in the reactor, and set the stirring speed to 60 PRM; (2) Maintain the mixer speed at 60 RPM, turn on the disperser, adjust the speed to 600 RPM, add the weighed hydrophilic fumed silica and calcium chloride dihydrate in sequence, and continue stirring and dispersing for 30 minutes; (3) Keep the speed of the mixer and disperser unchanged, and continue to add the measured polyacrylamide powder into the reactor. Continue stirring and dispersing for 30 minutes to obtain a quick-dissolving thickener suspension for fracturing. Example 5

[0023] The instant polymer suspension emulsion for fracturing mentioned in the present invention comprises the following components in parts by weight: 350 parts of N,N-dimethylformamide, 40 parts of water, 20 parts of inhibitor, 30 parts of hydrophilic fumed silica, 400 parts of polyacrylamide powder, the inhibitor is a mixture of calcium chloride, calcium chloride dihydrate, and magnesium chloride, in a weight ratio of 3:1:2.

[0024] The preparation process is as follows: The preparation method of the thickener suspension for fracturing of the present invention comprises the following steps: (1) Add the measured N,N-dimethylformamide and water into the reactor, turn on the stirring motor in the reactor, and set the stirring speed to 60 PRM; (2) Maintain the mixer speed at 60 RPM, turn on the disperser, adjust the speed to 600 RPM, add the weighed hydrophilic fumed silica and calcium chloride dihydrate in sequence, and continue stirring and dispersing for 30 minutes; (3) Keep the speed of the mixer and disperser unchanged, and continue to add the measured polyacrylamide powder into the reactor. Continue stirring and dispersing for 30 minutes to obtain a quick-dissolving thickener suspension for fracturing.

[0025] Comparative Example 1 (1) Add 564 parts of No. 5 white oil into the reactor, turn on the stirring motor in the reactor, and set the stirring speed to 60 rpm; (2) Maintain the mixer speed at 60 RPM, turn on the disperser, adjust the speed to 600 RPM, add 10 parts of Span 80, 6 parts of diethylene glycol butyl ether and 20 parts of organic soil in sequence, and continue stirring and dispersing for 30 minutes; (3) Keep the speed of the mixer and disperser unchanged, and continue to add 400 parts of polyacrylamide powder to the reactor. Continue stirring and dispersing for 30 minutes to obtain an oil-based thickener suspension.

[0026] Performance Test: (1) Test of heat and shear resistance: Use tap water to prepare a solution with a suspension volume concentration of 1.0%. Place the solution in a high-temperature and high-pressure rheometer slurry cup and heat it to 120°C at a heating rate of 3°C / min while maintaining a shear rate of 170 s -1 , until the total shear time reaches 2 hours. The test result is 35 mPa·s.

[0027] (2) Hydration rate test: Use tap water to prepare a solution with a mass percentage concentration of 0.3%. Add the required tap water to the mixer cup, adjust the mixer speed to 600 rpm, add the thickener suspension and stir for 10 seconds, pour the solution in the mixer cup into the rotary viscometer cup within the next 10 seconds, and install the rotary viscometer. Start rotating the viscometer at a speed of 300 rpm, and then read it every 5 seconds until the reading stabilizes. The test results show that the time for Example 2 to reach viscosity stability is only 105 seconds, while the oil-based thickener suspension of the comparative example takes 205 seconds.

[0028] The above are only some preferred embodiments of the present invention. Any person skilled in the art may modify the above technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modifications or equivalent transformations made according to the technical solutions of the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A quick-dissolving thickener suspension for fracturing, characterized in that The composition comprises the following components in parts by weight: 350-550 parts of N,N-dimethylformamide solvent, 30-100 parts of water, 10-30 parts of suspending agent, 10-50 parts of inhibitor, and 350-500 parts of polymer powder; the polymer powder is made of polyacrylamide.

2. The instant thickener suspension for fracturing according to claim 1, characterized in that: The particle size of the polyacrylamide powder is ≤125 μm, and the moisture content of the polyacrylamide powder is ≤10%.

3. The instant thickener suspension for fracturing according to claim 2, characterized in that: The suspending agent is magnesium aluminum silicate or silicon dioxide, or a mixture of the two.

4. The instant thickener suspension for fracturing according to claim 3, characterized in that: The silicon dioxide is hydrophilic fumed silicon dioxide.

5. The instant thickener suspension for fracturing according to claim 4, characterized in that: The inhibitor includes any one or more of calcium chloride, calcium chloride dihydrate, magnesium chloride and magnesium chloride hexahydrate.

6. The method for preparing the instant thickener suspension for fracturing according to claim 5, characterized in that The steps include: (1) Add N,N-dimethylformamide solvent and water into the reactor, turn on the stirring motor in the reactor, and set the stirring speed to 60 rpm; (2) Maintain the mixer speed at 60 RPM, turn on the disperser, adjust the speed to 600 RPM, add the suspending agent and inhibitor in sequence, and continue stirring and dispersing for 30 minutes; (3) Keep the speed of the mixer and disperser unchanged, continue to add polyacrylamide powder to the reactor, continue stirring and dispersing for 30 minutes after adding, and obtain a quick-dissolving thickener suspension for fracturing.

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