Discharge aiding agent for acid fracturing and preparation method thereof

Abstract

The invention relates to the technical field of oilfield chemistry, in particular to a discharge aiding agent for acid fracturing and a preparation method thereof.The discharge aiding agent for acid fracturing comprises, by mass, 10 parts of composite surfactant and the balance water; the composite surfactant is prepared from the following raw materials: 80wt%-95wt% of an anionic surfactant, 0-10wt% of a head hydroxyl cationic surfactant and 0-10wt% of a betaine type surfactant. According to the discharge aiding agent for acid fracturing and the preparation method of the discharge aiding agent, the surface and interface tension of an aqueous solution can be effectively reduced, the technical specification of the discharge aiding agent for acid fracturing is met, the preparation method is easy and convenient to operate, the raw materials are green and degradable, environmental pollution is avoided, industrial production, popularization and application are facilitated, and the discharge aiding agent has good application prospects. And the market prospect is wide.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemistry and is a drainage aid for acid fracturing and a preparation method thereof. Background Art

[0002] Acid fracturing transformation technology is an important measure for the efficient development of oil and gas fields. It is the main technical means to achieve the exploration and development of unconventional oil and gas resources, increase and stabilize the production of conventional oil and gas fields, and improve the effect of reservoir transformation. In the process of acid fracturing, it is usually necessary to rely on the formation pressure to quickly discharge the return fluid in the well to the ground. When the formation pressure gradually decreases, the return rate decreases significantly, and the residue in the return fluid will cause blockage after precipitation, resulting in secondary pollution of the formation, which seriously affects the construction efficiency and the effect of acid fracturing transformation. In order to solve the problem of difficulty in returning the return fluid after oil acid fracturing, the use of drainage aids is a conventional method.

[0003] A drainage aid is a type of fracturing fluid additive that can effectively reduce surface tension and interfacial tension, reduce capillary resistance, increase flowback rate and flowback ratio, and thus reduce formation damage. There are many types of drainage aids currently used at home and abroad, but most of them are prepared by compounding fluorocarbon surfactants with other surfactants. Fluorocarbon surfactants have high surface activity and can reduce surface tension to 23mN / m. However, they are expensive, difficult to degrade, and have high biological toxicity. Therefore, the European Union banned the use of fluorocarbon surfactants in June 2008. In view of this, the development of a green and environmentally friendly drainage agent system has become an urgent problem to be solved. Summary of the invention

[0004] The present invention provides a drainage aid for acid fracturing, which overcomes the deficiencies of the prior art and can effectively solve the problems of the prior drainage aid for acid fracturing being expensive and difficult to degrade.

[0005] One of the technical solutions of the present invention is achieved through the following measures: a drainage aid for acid fracturing, wherein the raw materials, calculated by weight, include: 10 parts of a composite surfactant and the rest is water; the composite surfactant raw material includes 80wt% to 95wt% of anionic surfactant, 0 to 10wt% of a head hydroxyl cationic surfactant, and 0 to 10wt% of a betaine type surfactant; the required amounts of anionic surfactant, head hydroxyl cationic surfactant, betaine type surfactant and water are mixed, and stirred evenly at room temperature to obtain a drainage aid for acid fracturing.

[0006] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions:

[0007] The anionic surfactant is sodium fatty alcohol polyoxyethylene ether carboxylate, and its chemical structure is:

[0008]

[0009] The above R1 is C 12 To C 18 Aliphatic hydrocarbon group, n is an integer greater than or equal to 2.

[0010] The chemical structural formula of the above-mentioned head hydroxyl cationic surfactant is:

[0011]

[0012] The above R2 is C 12 To C 16 An aliphatic hydrocarbon group, X is a halogen chlorine or bromine.

[0013] The betaine-based surfactant is N-alkyl-N,N-dimethylammonium acetate, and its chemical structure is:

[0014]

[0015] The above R3 is C 12 To C 16 of aliphatic hydrocarbon groups.

[0016] The second technical solution of the present invention is achieved through the following measures: a method for preparing a drainage aid for acid fracturing, comprising the following steps: mixing the required amounts of anionic surfactant, head hydroxyl cationic surfactant, betaine type surfactant and water, stirring evenly at room temperature to obtain a drainage aid for acid fracturing.

[0017] The invention provides a drainage aid for acid fracturing and a preparation method thereof. The drainage aid of the invention can effectively reduce the interfacial tension of the aqueous solution surface and meet the technical specifications of the drainage aid for acid fracturing. The preparation method is simple to operate, the raw materials are green and degradable, and no environmental pollution is caused. The invention is conducive to industrial production and promotion and application, and has broad market prospects. DETAILED DESCRIPTION

[0018] The present invention is not limited by the following embodiments, and the specific implementation method can be determined according to the technical scheme of the present invention and the actual situation. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all chemical reagents and chemicals known and used in the prior art; unless otherwise specified, the percentages in the present invention are all mass percentages; unless otherwise specified, the solutions in the present invention are all aqueous solutions with water as the solvent, for example, hydrochloric acid solution is a hydrochloric acid aqueous solution; the normal temperature and room temperature in the present invention generally refer to a temperature of 15°C to 25°C, and are generally defined as 25°C.

[0019] The present invention will be further described below in conjunction with embodiments:

[0020] Embodiment 1: The drainage aid for acid fracturing comprises, by weight, 100 parts of composite surfactant and the rest of water; the composite surfactant raw material comprises 80wt% to 95wt% of anionic surfactant, 0 to 10wt% of hydroxyl cationic surfactant and 0 to 10wt% of betaine surfactant; the required amounts of anionic surfactant, hydroxyl cationic surfactant, betaine surfactant and water are mixed and stirred evenly at room temperature to obtain the drainage aid for acid fracturing.

[0021] Example 2: As an optimization of the above example, the anionic surfactant is sodium fatty alcohol polyoxyethylene ether carboxylate, and the chemical structural formula is:

[0022]

[0023] Example 3: As an optimization of the above Example 2, R1 is C 12 To C 18 Aliphatic hydrocarbon group, n is an integer greater than or equal to 2.

[0024] Example 4: As an optimization of the above example, the chemical structural formula of the head hydroxyl cationic surfactant is:

[0025]

[0026] Embodiment 5: As an optimization of the above 4 embodiments, R2 is C 12 To C 16 An aliphatic hydrocarbon group, X is a halogen chlorine or bromine.

[0027] Example 6: As an optimization of the above example, the betaine-type surfactant is N-alkyl-N,N-dimethylammonium acetate, and the chemical structural formula is:

[0028]

[0029] Example 7: As an optimization of the above Example 6, R3 is C 12 To C 16 aliphatic hydrocarbon group.

[0030] Example 8: The method for preparing the drainage aid for acid fracturing comprises the following steps: mixing the required amounts of anionic surfactant, head hydroxyl cationic surfactant, betaine type surfactant and water, stirring evenly at room temperature to obtain the drainage aid for acid fracturing.

[0031] Embodiment 9:

[0032] Weigh 9.5 parts by mass of sodium lauryl polyoxyethylene ether (3) carboxylate and 0.5 parts by mass of N-hexadecyl-N,N-dimethylhydroxyethyl ammonium chloride and dissolve them in 90 parts by mass of water. Stir at room temperature and dissolve them uniformly to prepare 100 parts by mass of a drainage aid for acid fracturing.

[0033] The experimental test results of the acid fracturing drainage agent show that the surface tension of the acid fracturing drainage agent at a concentration of 0.3% by mass is 23.759 mN / m, and the interfacial tension is 0.178 mN / m, which meets the industry use standards for non-fluorocarbon drainage agents.

[0034] Embodiment 10:

[0035] Weigh 9 parts by mass of sodium lauryl polyoxyethylene ether (3) carboxylate and 1 part by mass of N-hexadecyl-N,N-dimethylammonium acetate and dissolve them in 90 parts by mass of water. Stir at room temperature to dissolve them uniformly to prepare 100 parts by mass of a drainage aid for acid fracturing.

[0036] The experimental test results of the acid fracturing drainage agent show that the surface tension of the acid fracturing drainage agent at a concentration of 0.3% by mass is 23.146 mN / m, and the interfacial tension is 0.061 mN / m, which meets the industry use standards for non-fluorocarbon drainage agents.

[0037] Embodiment 11:

[0038] Weigh 9 parts by mass of sodium lauryl polyoxyethylene ether (3) carboxylate, 0.5 parts by mass of N-hexadecyl-N,N-dimethylhydroxyethyl ammonium chloride, and 0.5 parts by mass of N-hexadecyl-N,N-dimethyl ammonium acetate, and dissolve them in 90 parts by mass of water. Stir at room temperature to uniformly dissolve them to prepare 100 parts by mass of a drainage aid for acid fracturing.

[0039] The experimental test results of the acid fracturing drainage agent show that the surface tension of the acid fracturing drainage agent at a concentration of 0.3% by mass is 22.593 mN / m, and the interfacial tension is 0.283 mN / m, which meets the industry use standards for non-fluorocarbon drainage agents.

[0040] Embodiment 12:

[0041] Weigh 8 parts by mass of sodium hexadecanol polyoxyethylene ether (2) carboxylate, 1 part by mass of N-tetradecyl-N,N-dimethylhydroxyethyl ammonium bromide, and 1 part by mass of N-hexadecyl-N,N-dimethylammonium acetate, and dissolve them in 90 parts by mass of water. Stir at room temperature to uniformly dissolve them to prepare 100 parts by mass of a drainage aid for acid fracturing.

[0042] The experimental test results of the acid fracturing drainage agent show that the surface tension of the acid fracturing drainage agent at a concentration of 0.3% by mass is 22.292 mN / m, and the interfacial tension is 0.078 mN / m, which meets the industry use standards for non-fluorocarbon drainage agents.

[0043] Embodiment 13:

[0044] Weigh 8 parts by mass of sodium stearyl alcohol polyoxyethylene ether (2) carboxylate, 1 part by mass of N-dodecyl-N,N-dimethylhydroxyethyl ammonium bromide, and 1 part by mass of N-hexadecyl-N,N-dimethylammonium acetate, and dissolve them in 90 parts by mass of water. Stir at room temperature to uniformly dissolve them to prepare 100 parts by mass of a drainage aid for acid fracturing.

[0045] The experimental test results of the acid fracturing drainage agent show that the surface tension of the acid fracturing drainage agent at a concentration of 0.3% by mass is 23.629 mN / m, and the interfacial tension is 0.388 mN / m, which meets the industry use standards for non-fluorocarbon drainage agents.

[0046] In summary, the present invention provides a drainage aid for acid fracturing and a preparation method thereof. The surfactants in the raw materials of the drainage aid for acid fracturing are all degradable, non-biotoxic, green and environmentally friendly, and can effectively avoid the damage of fluorocarbon drainage aids to the environment and organisms; different types of surfactants in the raw materials have good composite synergistic characteristics, which can effectively reduce the surface and interfacial tension of oil and gas field fracturing fluids. The surfactants in the raw materials only account for 10% of the total amount of the drainage aid for acid fracturing. At the same time, the dosage of betaine-type surfactants is low, which effectively reduces the cost of use. The drainage aid for acid fracturing does not contain flammable, explosive, and volatile substances, and is suitable for acid fracturing operations under different operating environments.

[0047] 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 reduced according to actual needs to meet the requirements of different situations.

Claims

1. A drainage agent for acid fracturing, Features The raw materials include, by weight, 10 parts of a composite surfactant and the rest of water; the composite surfactant raw material includes 80wt% to 95wt% of anionic surfactant, 0 to 10wt% of a hydroxyl cationic surfactant, and 0 to 10wt% of a betaine surfactant; required amounts of anionic surfactant, hydroxyl cationic surfactant, betaine surfactant and water are mixed, and stirred evenly at room temperature to obtain a drainage agent for acid fracturing.

2. The acid fracturing drainage agent according to claim 1, Features The anionic surfactant is sodium fatty alcohol polyoxyethylene ether carboxylate, and its chemical structure is:

3. The acid fracturing drainage agent according to claim 2, Features R 1 C 12 To C 18 Aliphatic hydrocarbon group, n is an integer greater than or equal to 2.

4. The drainage aid for acid fracturing according to any one of claims 1 to 3, Features The chemical structure of the hydroxyl cationic surfactant is:

5. The drainage aid for acid fracturing according to claim 4, Features R 2 C 12 To C 16 An aliphatic hydrocarbon group, X is a halogen chlorine or bromine.

6. The drainage aid for acid fracturing according to any one of claims 1 to 5, Features Betaine-based surfactants are N-alkyl-N,N-dimethylammonium acetate, with the chemical formula:

7. The drainage aid for acid fracturing according to claim 6, Features R 3 C 12 To C 16 of aliphatic hydrocarbon groups.

8. A method for preparing the drainage aid for acid fracturing according to any one of claims 1 to 7, Features The method comprises the following steps: mixing required amounts of anionic surfactant, head hydroxyl cationic surfactant, betaine type surfactant and water, and stirring them uniformly at room temperature to obtain a drainage aid for acid fracturing.

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