Polymer emulsion low-temperature gel breaking activator and preparation method thereof

Abstract

The invention relates to the technical field of oilfield chemistry, in particular to a polymer emulsion low-temperature gel breaking activating agent and a preparation method thereof.The polymer emulsion low-temperature gel breaking activating agent is prepared from, by mass, 1%-5% of inorganic activating agent, 0.5%-5% of organic activating agent, 0-20% of pH buffering agent and the balance water; the polymer emulsion low-temperature gel breaking activator is obtained according to the following method: at room temperature, adding the organic activator, the inorganic activator and the pH buffer agent with required amounts into water, and uniformly stirring to obtain the polymer emulsion low-temperature gel breaking activator. The invention provides the polymer emulsion low-temperature gel breaking activator and the preparation method thereof, the polymer emulsion low-temperature gel breaking activator can realize thorough gel breaking of the polymer emulsion at a low temperature of 10-50 DEG C, and has the advantages of low cost, small dosage, controllable gel breaking time, stable performance and the like, and the preparation method is simple to operate and suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry, and in particular to a polymer emulsion low-temperature gel breaking activator and a preparation method thereof. Background Art

[0002] Hydraulic fracturing is one of the primary methods for increasing oil and gas well production. Timely and thorough fracturing of the fracturing fluid during fracturing operations is a key factor in determining its success. Currently, conventional fracturing fluid breaking technology is used for low-temperature (15°C to 50°C) and shallow (300m to 1500m) reservoirs both domestically and internationally. However, this technology suffers from issues such as long and incomplete breaking times, long and incomplete flowback, and significant reservoir damage. Polymer emulsions are particularly difficult to break at low temperatures due to the presence of emulsifiers.

[0003] Water-based fracturing fluid breakers primarily use peroxides, such as ammonium persulfate and sodium persulfate. Their breaking rate depends on the decomposition rate of the persulfate, which in turn depends on the reservoir temperature. At 50°C, the half-life of the persulfate is nearly tenfold longer than at 60°C, significantly reducing its decomposition rate. This can lead to incomplete breaking or high residue levels. To improve low-temperature breaking, increasing the peroxide concentration and combining it with a low-temperature activator are common approaches, but these approaches are ineffective and pose significant risks, such as increased construction risks and the potential for increased hydrogen sulfide content in the formation. Furthermore, activators often contain ferric or ferrous ions. The iron ions generated by the redox reaction can significantly affect the performance of the fracturing fluid and can also precipitate iron hydroxide, causing reservoir damage.

[0004] Therefore, developing a suitable low-temperature polymer emulsion gel-breaking activator to ensure timely and thorough emulsion breaking and reduce the viscosity and residue content of the gel-breaking fluid has significant practical significance for the promotion and application of slick water fracturing fluid and can significantly reduce the cost of fracturing construction. Summary of the Invention

[0005] The present invention provides a polymer emulsion low-temperature gel-breaking activator and a preparation method thereof, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problems of incomplete gel-breaking or high residue content of the existing gel-breaking agents at low temperatures.

[0006] One of the technical solutions of the present invention is achieved through the following measures: a polymer emulsion low-temperature gel-breaking activator, the raw materials of which are composed, by mass percentage, of: 1% to 5% of an inorganic activator, 0.5% to 5% of an organic activator, and 0 to 20% of a pH buffer, with the remainder being water; the activator is obtained by the following method: at room temperature, the required amounts of the organic activator, the inorganic activator, and the pH buffer are added to water, and the mixture is stirred evenly to obtain the polymer emulsion low-temperature gel-breaking activator.

[0007] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions: The above-mentioned inorganic activator is sulfite.

[0008] The organic activator is one or more of ethanolamine, diethanolamine, tetramethylethylenediamine, polyethyleneimine, hydrazine hydrate, hydroxylamine, dimethylhydroxylamine, and diethylhydroxylamine.

[0009] The pH buffer is an ammonium salt.

[0010] The inorganic activator is one or more of ammonium sulfite, sodium sulfite, sodium bisulfite and potassium sulfite.

[0011] The pH buffer is one or more of ammonium chloride, ammonium sulfate, ammonium bicarbonate, ammonium acetate, ammonium formate, and ammonium oxalate.

[0012] The second technical solution of the present invention is achieved through the following measures: a preparation method of a polymer emulsion low-temperature gel-breaking activator, which is carried out according to the following steps: adding the required amount of organic activator, inorganic activator and pH buffer to water, and stirring evenly to obtain the polymer emulsion low-temperature gel-breaking activator; wherein, in the raw materials, by mass percentage, the inorganic activator is 1% to 5%, the organic activator is 0.5% to 5% and the pH buffer is 0 to 20%, and the rest is water.

[0013] The present invention provides a low-temperature gel-breaking activator for polymer emulsion and a preparation method thereof. The low-temperature gel-breaking activator for polymer emulsion can achieve complete gel breaking of polymer emulsion at low temperatures of 10°C to 50°C, has the advantages of low cost, small dosage, controllable gel-breaking time and stable performance. The preparation method is simple to operate and is suitable for industrial production. DETAILED DESCRIPTION

[0014] The present invention is not limited to the following embodiments; specific implementation methods may be determined based on the technical solutions of the present invention and actual conditions. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all known and commonly used chemical reagents and chemicals in the prior art. Unless otherwise specified, percentages in the present invention are by mass. Normal temperature and room temperature in the present invention generally refer to temperatures between 15°C and 25°C, with 25°C generally defined as the room temperature.

[0015] The present invention will be further described below in conjunction with the embodiments: Example 1: The polymer emulsion low-temperature gel-breaking activator comprises the following raw materials, calculated by mass percentage: 1% to 5% of an inorganic activator, 0.5% to 5% of an organic activator, and 0 to 20% of a pH buffer, with the remainder being water; the activator is obtained by the following method: at room temperature, the required amounts of the organic activator, the inorganic activator, and the pH buffer are added to water, and the mixture is stirred evenly to obtain the polymer emulsion low-temperature gel-breaking activator.

[0016] Example 2: As an optimization of the above example, the inorganic activator is sulfite.

[0017] Example 3: As an optimization of the above example, the organic activator is one or more of ethanolamine, diethanolamine, tetramethylethylenediamine, polyethyleneimine, hydrazine hydrate, hydroxylamine, dimethylhydroxylamine, and diethylhydroxylamine.

[0018] Example 4: As an optimization of the above example, the pH buffer is an ammonium salt.

[0019] Example 5: As an optimization of the above example, the inorganic activator is one or more of ammonium sulfite, sodium sulfite, sodium bisulfite, and potassium sulfite.

[0020] Example 6: As an optimization of the above example, the pH buffer is one or more of ammonium chloride, ammonium sulfate, ammonium bicarbonate, ammonium acetate, ammonium formate, and ammonium oxalate.

[0021] Example 7: The preparation method of the polymer emulsion low-temperature gel-breaking activator is carried out according to the following steps: adding the required amount of organic activator, inorganic activator and pH buffer to water, and stirring evenly to obtain the polymer emulsion low-temperature gel-breaking activator; wherein, in the raw materials, by mass percentage, the inorganic activator is 1% to 5%, the organic activator is 0.5% to 5% and the pH buffer is 0 to 20%, and the rest is water.

[0022] Example 8: The polymer emulsion low-temperature gel-breaking activator comprises, by mass percentage, 5% of an inorganic activator (4% sodium sulfite + 1% ammonium sulfite), 5% of an organic activator (0.9% hydrazine hydrate + 0.1 polyethyleneimine + 4% hydroxylamine) and 20% of a pH buffer (5% ammonium formate + 15% ammonium sulfate), with the remainder being water.

[0023] The preparation method for this polymer emulsion low-temperature gel-breaking activator is as follows: at room temperature (approximately 25°C), add 70 parts of water to a reactor, start stirring, and slowly add 0.9 parts of hydrazine hydrate. After the temperature stabilizes, add 0.1 parts of polyethyleneimine, 4 parts of hydroxylamine, 5 parts of ammonium formate, 15 parts of ammonium sulfate, 4 parts of sodium sulfite, and 1 part of ammonium sulfite. Stir and react for 0.5 to 1 hour to obtain the polymer emulsion low-temperature gel-breaking activator. The prepared polymer emulsion low-temperature gel-breaking activator is stored in blue tonneau drums in a shaded, cool, and well-ventilated area. Indoor performance testing of the polymer emulsion low-temperature gel-breaking activator is performed, and the results are shown in Table 1. The indoor test results in Table 1 show that the polymer emulsion low-temperature gel-breaking activator breaks polymer emulsions at temperatures between 10°C and 50°C, with a post-break viscosity of less than 3 mPa·s, meeting industry standards for gel-breaking fluids.

[0024] Example 9: The polymer emulsion low-temperature gel-breaking activator comprises, by mass percentage, 5% of an inorganic activator (4% sodium sulfite + 1% ammonium sulfite), 5% of an organic activator (1% diethanolamine + 4% hydroxylamine), and 10% of a pH buffer (1% ammonium oxalate + 9% ammonium chloride), with the remainder being water.

[0025] The preparation method for this polymer emulsion low-temperature gel-breaking activator is as follows: At room temperature (approximately 25°C), add 80 parts of water to a reactor, start stirring, and slowly add 1 part of diethanolamine. After the temperature stabilizes, add 4 parts of hydroxylamine, 1 part of ammonium oxalate, 9 parts of ammonium chloride, 4 parts of sodium sulfite, and 1 part of ammonium sulfite. Continue stirring and react for 0.5 to 1 hour to obtain the polymer emulsion low-temperature gel-breaking activator. The prepared polymer emulsion low-temperature gel-breaking activator is stored in blue tonneau drums in a shaded, cool, and well-ventilated area. Indoor performance testing of this polymer emulsion low-temperature gel-breaking activator is performed, and the results are shown in Table 2. The indoor test results in Table 2 show that this polymer emulsion low-temperature gel-breaking activator breaks polymer emulsions at temperatures between 10°C and 50°C, with a post-break viscosity of less than 3 mPa·s, meeting industry standards for gel-breaking fluids.

[0026] Example 10: The polymer emulsion low-temperature gel-breaking activator comprises, by mass percentage, 5% of an inorganic activator (4% sodium sulfite + 1% potassium sulfite), 3% of an organic activator (0.5% polyethyleneimine + 2.5% dimethylhydroxylamine) and 10% of a pH buffer (1% ammonium oxalate + 9% ammonium acetate), with the remainder being water.

[0027] The preparation method for this polymer emulsion low-temperature gel-breaking activator is as follows: at room temperature (approximately 25°C), add 82 parts of water to a reactor, start stirring, and slowly add 0.5 parts of polyethyleneimine, 2.5 parts of dimethylhydroxylamine, 1 part of ammonium oxalate, 9 parts of ammonium acetate, 4 parts of sodium sulfite, and 1 part of potassium sulfite. Stirring and reacting are continued for 0.5 to 1 hour to obtain the polymer emulsion low-temperature gel-breaking activator. The prepared polymer emulsion low-temperature gel-breaking activator is stored in blue tonneau drums in a shaded, cool, and well-ventilated area. Indoor performance testing of this polymer emulsion low-temperature gel-breaking activator is performed, and the results are shown in Table 3. The indoor test results in Table 3 show that the polymer emulsion low-temperature gel-breaking activator breaks polymer emulsions at temperatures between 10°C and 50°C, with a post-break viscosity of less than 3 mPa·s, meeting industry standards for gel-breaking fluids.

[0028] Example 11: The polymer emulsion low-temperature gel-breaking activator comprises, by mass percentage, 2% of an inorganic activator (ammonium sulfite), 5% of an organic activator (1% hydrazine hydrate + 4% diethylhydroxylamine) and 10% of a pH buffer (1% ammonium bicarbonate + 9% ammonium formate), with the remainder being water.

[0029] The preparation method for this polymer emulsion low-temperature gel-breaking activator is as follows: at room temperature (approximately 25°C), add the required amount of water to a reactor, start stirring, and slowly add hydrazine hydrate. After the temperature stabilizes, add diethylhydroxylamine, ammonium bicarbonate, ammonium oxalate, and ammonium sulfite. Continue stirring and reacting for 0.5 to 1 hour to obtain the polymer emulsion low-temperature gel-breaking activator. The prepared polymer emulsion low-temperature gel-breaking activator is stored in blue tonneau drums in a shaded, cool, and well-ventilated area. Indoor performance testing of this polymer emulsion low-temperature gel-breaking activator is performed, and the results are shown in Table 4. The indoor test results in Table 4 show that the polymer emulsion low-temperature gel-breaking activator breaks polymer emulsions at temperatures between 10°C and 50°C, with a post-break viscosity of less than 3 mPa·s, meeting industry standards for gel-breaking fluids.

[0030] Example 12: The polymer emulsion low-temperature gel-breaking activator comprises, by mass percentage, 5% of an inorganic activator (sodium sulfite), 2% of an organic activator (0.5% hydrazine hydrate + 1.5% hydroxylamine), and the remainder is water.

[0031] The preparation method for this polymer emulsion low-temperature gel-breaking activator is as follows: At room temperature (approximately 25°C), add 93 parts of water to a reactor, start stirring, and slowly add 0.5 parts of hydrazine hydrate. After the temperature stabilizes, add 1.5 parts of hydroxylamine and 5 parts of sodium sulfite. Continue stirring and react for 0.5 to 1 hour to obtain the polymer emulsion low-temperature gel-breaking activator. The prepared polymer emulsion low-temperature gel-breaking activator is stored in blue tonneau drums in a shaded, cool, and well-ventilated area. Indoor performance testing of this polymer emulsion low-temperature gel-breaking activator is performed, and the results are shown in Table 2. The indoor test results in Table 2 indicate that this polymer emulsion low-temperature gel-breaking activator breaks polymer emulsions at temperatures between 10°C and 50°C, with a post-break viscosity of less than 3 mPa·s, meeting industry standards for gel-breaking fluids.

[0032] The polymer emulsion low-temperature gel-breaking activator of the present invention can achieve complete gel-breaking of polymer emulsions at low temperatures of 10°C to 50°C, and has the advantages of low cost, small dosage, controllable gel-breaking time, and stable performance. In addition, the raw material components will not precipitate in the formation, thus avoiding reservoir damage and expanding the scope of use of the activator. The preparation method is safe and reliable, simple to operate, has low equipment requirements, is easy to control and implement, and is suitable for industrial large-scale production.

[0033] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the requirements of different situations.

Claims

1. A polymer emulsion low temperature debonding activator, characterized in that The raw materials are composed of 1% to 5% of an inorganic activator, 0.5% to 5% of an organic activator and 0 to 20% of a pH buffer, and the rest is water; the raw materials are obtained by the following method: at room temperature, the required amount of the organic activator, the inorganic activator and the pH buffer are added to water, and the polymer emulsion low-temperature degelling activator is obtained after being stirred evenly.

2. The polymer emulsion low temperature debonding activator according to claim 1, characterized in that The inorganic activator is sulfite.

3. The polymer emulsion low temperature debonding activator according to claim 1 or 2, characterized in that The organic activator is one or more of ethanolamine, diethanolamine, tetramethylethylenediamine, polyethyleneimine, hydrazine hydrate, hydroxylamine, dimethylhydroxylamine and diethylhydroxylamine.

4. The polymer emulsion low temperature debonding activator according to claim 1, 2 or 3, characterized in that The pH buffer was an ammonium salt.

5. The polymer emulsion low temperature debonding activator according to claim 2, characterized in that The inorganic activator is one or more of ammonium sulfite, sodium sulfite, sodium bisulfite and potassium sulfite.

6. The polymer emulsion low temperature debonding activator according to claim 4, characterized in that The pH buffer is one or more of ammonium chloride, ammonium sulfate, ammonium bicarbonate, ammonium acetate, ammonium formate, and ammonium oxalate.

7. A method for preparing a polymer emulsion low-temperature debonding activator according to any one of claims 2 to 6, characterized in that The method is carried out according to the following steps: adding the required amount of organic activator, inorganic activator and pH buffer into water, stirring evenly to obtain the polymer emulsion low-temperature degelling activator; wherein, by mass percentage, the inorganic activator in the raw material is 1% to 5%, the organic activator is 0.5% to 5% and the pH buffer is 0 to 20%, and the rest is water.

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